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Full text of "History and construction of the electrical substation of the Pennsylvania Railroad at Landover, Maryland / by Louis Francis Flagg"

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0? THE 



MAY 3, 1935 



The author has attempted to present in this thesis a clear con- 
ception of the part that Landover Substation plays in the electrification of 

the Pennsylvania Railroad. The subject is covered in as much detail as avail- 
able information would permit. This was done with the idea of using the thesis 
as a future reference since the details concerning the substation are so dif- 
ficult to obtain. 

Many difficulties were encountered in obtaining information for 
this thesis because much of the apparatus was designed especially for the elec- 
trification and henoe very little is written about it. She plans of the substa- 
tion are secretive and are not obtainable. The cost is also unobtainable, and 
estimates varied from a quarter to a half million dollars . 

In order to make this presentation clearer and more interesting, 
diagrams and pictures were added. 

The author suggests that the reader might get a better understand- 
ing of this project if the thesis " The History and Methods of Electrification 
of the Pennsylvania Railroad between Baltimore and Washinton, D.C." by d II. 
Ludwig is read first. 




History and Construction 


Electrical Layout 


High Side Layout 


Low Side Layout 






Direct Current Supply 








Oil Circuit Breakers 


High Speed Breakers 




Lightning Protection 


Relay Operation 


Preliminary Tests 

• 46 



Signal Power 






- 3- 

Substation from road leading to it 

Substation from loi car across the tracks 



The electrical substation of the Pennsylvania Railroad at Landover, 
Maryland is an important link in a chain of substations necessary for the 
successful electrification of the railroad. When the Pennsylvania Railroad 
decided upon electrification, the entire project was turned over to the 
electrification desi^ne^s, Gibbs and Hill of New York. They were confronted 
with the problem of supplying 1 power to the trains over lone stretches unless 
intermediate power supply stations were added. They decided to draw from the 
large power supply at Safe Harbor and transmit it at high voltage to electrical 
substations placed at strategic points approximately ten miles apart. Landova- 
is one of the key points on the railroad because it is there that the passenger 
and freifht lines into Washington split. It also is about ten miles from the 
neuTMt main control point in either direction. Therefore it was essential to 
use Landover as one substation location. 

After Landover had been decided upon as the general location its 
exact position had to be determined and a center line laid down. Thi» line 
and a bench mark in the vicinity along with the blue print plans of the sub- 
station formed the basis from which the station was built. The job of sur- 
veying this plot was given to an inspector whose duty it w^s to see that 
everything went into the substation according to the blue prints unless alter- 
ations were necessary. To actually put in the materials and control the crew 
a foreman was assigned. The crew itself v/as made up of men who had worked for 
the division previously, some of them furloughed conductors and engineers. 
However the Landover crew also had a few outside men who v/e^e more experienced. 
These wert brought in by giving them a division job and then furloughing them 
after one day, thus covering the rules. 


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Train with new type electric locomotive 


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3 team train under a signal 

Hew type spot signal 







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1 "fiSE ^ 1 

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Placing concrete foundations 


Cl earing the land for the substation was done in April 1934 but 
actual work on the station was started about the middle of June 19?4. One 
difficulty arose almost immediately thereafter. The substation was to be 
built over a section of a state road and permission to close this road could 
only be obtained through a court order. The State Roads Commission agreed to 
this but court did not convene until September. In the meantime a road was 
built around the station and a detour sign placed on the old road although 
it was not officially closed. The court order granting the road right of 
way to the railroad was finally issued about the first of October. In the 
meantime work on the substation had progressed without delay. In fact all 
the foundations had been placed and most of the steel work erected at that 

The actual laying out of the substation was begun by surveying to 
obtain all foundation locations. Then followed excavating which was done 
entirely by manual labor. After the excavation another difficulty was real- 
ized* Due to the swampy region the clay was so soft that a reenforcement 
rod could be shoved in out of sight. To eliminate this difficulty the holes 
were dug deeper and about a foot of stone was placed on top of the soft clay 
before the concrete was poured. 

The concrete for this job was mixed by the crew itself with a 
ratio of 1:2.5:3.5. The steel work, both high and low structures, was placed 
in the foundations by huge cranes. The 90 foot steel columns were carefully 
trued up with instruments and fastened together with the cross pieces. After 
they were all linked together there was very little chance of any movement to 
cause a change in alignment. 

Before any of the heavy equipment was brought in a service track 
which branched off the main track was laid into the substation. Then four 
tracks were laid perpendicular to the service track, one leading to each 




Placing steel work with cranes (A, B, C) 
Working on "E" switches ( D ) 


main transformer. These large transformers were "brought Into the station on 
flat-cars "by way of the service track. Each was then lowered to its own track 
and moved along the track until directly over its foundation where it was to 
be permanently located. Circuiti breakers were also brought in by train and 
placed on their foundations from there. All other heavy equipment was treated 

The control building located directly in the center of the substation 
was built of cement blocks which were made by using cinders instead of stone 
for the coarse aggregates. The building is a one story structure about 22 feet 
wide, 26 feet long, and 1? feet high with concrete floors and roof. It has 
three rooms in all. One takes up about half the building and contains a Bwitch 
control board and a motor-generator set. The other two take up the remaining 
half about evenly. One of these is the battery room and the other just a 

In order to improve the surface of the Bub station ground about 
8 inches of cinders were placed on top of it. These were brought in by train 
and spread over the entire inclosure. A high fence with barbed wire at the 
top was placed around the entire substation to keep inquisitive people and 
animals out of danger. 

When the Bubstation had been completed sufficiently a D.C. test waB 
made. This was done at handover about the middle of October. Before the station 
was actually placed in service it was also necessary to make an A.C. test as a 
final check on all apparatus and circuits. This vas done from January 18 to 
25, 19^5. For this test the substation was energized on January 18 at about 
nine o'clock in the morning for the first time. The control of the station 
was turned over to the tower board on February 2 and under normal conditions 
has operated from there ever since. The entire project minus a few details 


Substatlon in early stages of 

Substation when practically completed 


Internal view before completion 

Substation just "before completion 

from box car across tracks 

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Le** S"?rtAcStt4irt 

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5ej" ir/'c e 7V o c /f 

Corf tr-e i 







Ground Pi 

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euch as a lightning pole which has not been placed yet was officially completed 
about the middle of March, 1935. 

At the present time the substation is controlled from the tower but 
an electrician maintainer and his helper work at the station 8 hours a day for 
6 days a week* Their job is to inspect and take care of the substation* They 
may also be called on to help in case of trouble, but up to the present time 
Land over Substation has had no serious trouble of any kind. 


In order to more easily understand the layout of the substation it is 
first necessary to understand the system of numbers used throughout the entire 
chain of substations. Each substation is designated by a number, these numbers 
running in sequence going south. Thus Severn Substation is number 22, Bowie 
is number 23, Landover is number 24. and Capital is number 25. All transmission 
lines between substations are designated by the number of the more southern 
station. Thus the two transmission lines, called 1 and 2, are called 124 and 
224 between Bowie and Landover. Between Landover and Capital these lines are 
125 and 225. This system makes it easier for designating switches and other 
apparatus • 

High Side Layout 

low tht fi r8 t consideration in the electrical layout of the sub- 
station is the me:-ns of bringing power into the station. This is done with 
the two transmission lines, 124 and 224, carrying 132,000 volts A.C. The first 
switches on these 132 K7 lines are ground switches 1240 and 2240. On the same 

steel framework the lines must pass through main line switches 124 and 224. 
* See diagram of connections 

ciiofnc DirTiacN co. 


From there these lines pass to the other side of the station where they pass 
through switches 125 and 225. There are also ground switches beyond, numbers 
125G and 225G. The lines lead from there to Capital Substation in Washington. 
Thus it is possible by opening switches 125 and 225 to cut off the entire 
'power supply to Capital. Likewise by opening 124 and 224 the supply to Land- 
over is cut off. The 132 KV lines are tied together through two switches, the 
switch nearest line 1 is called 12 and that nearest line 2 is 21, showing that 
the switches are from lines 1 to 2 and 2 to 1 respectively. A lead taken off the 
132 KV bus of line 1 goes to transformers 1 and 1A after passing through the 
so called "H" switches 1H and 1AH. A lead taken off the V-Z KV line 2 goes 
to transformers 2 and 2A through the switches IE and 2AH. That completes the 
high side (1?2 KV) layout of the substation. 

Low Side Layout 

The secondary of each transformer is connected to a low side bus 
and a rail return bus through an "L" circuit breaker. Each M L'* breaker is 
numbered according to the transformer which it connects* They are 1L, 1AL, 
2L, 2AL. Each of these breakers is Isolated by switches to afford protection 
while working on it. There are two 12 KV buses, numbers 24 and 25. Alternate 
transformers are connected to these. That is, transformers 1 and 2A supply 
bus 25 while 1A and 2 Bupply bus 24. Connected in this fashion the 1^2 KV 
line 1 supplies bus section 25 through transformer 1 and bus section 24 through 
1A. Similarly line 2 supplies both buses through 2A and2. The bus sections 
may be connected together by the rt BB" bus-tie circuit breaker which is also 
isolated by switches. All the trolley feeders are taken off the 12 KV bus 
sections through JHA circuit breakers. These breakers are numbered according 
to the bus section and the trolley supplied through the breaker. Thus the 


breaker feeding the trolley on track 1 going north is 2401, for track 2 it 
18 2402, and for track 3 it is 240?. All feeders going north are from "bus 
24 and those going south from bus 25. There are four tracks leading south 
from Landover, two down the Anacostia Branch (freight line) to Potomac Yards 
and two down the Llagruder Branch . (passenger line) to Union Station. The 
freight line is fed through breakers 2501 and 2502, and the passenger line is 
fed through 250? and 2504. Another line leading south to a sec tionali zing 
switch between Landover and Union Station is fed through 25T. There are also 
two other JRA breakers, LI from bus 25 and L2 from bus 24, that feed an island 
section at Landover, TMb is merely a feed for a section containing switches 
that are not coi — ected to the main trolleys. The feeders from LI and L2 are 
connected by a twitch, L12, so both may be operated from either bus section. 
Each "^A breaker may he isolated fcy its "B" and "P" switches. The "B H switch 
disconnects the breaker from its bus section and the rt P r * from its trolley 
feeders. The^e is also a "T" switch in each trolley feeder to permit work on 
the trolley feeder right up to the point where it leaves t?ie station. The 
"B", *f" t and "T" switches are numbered the same as the breakers. Thus 
breaker 2401 is isolated by opening 2401B and 240 IP. In addition to the 
trolley feeders e^ch 12 KV bus supplies a service transformer and a potential 
transformer. These are numbered 524, P24, 525, and P25. Each service trans- 
former has 220 volts across its secondary with a center tap to give 110 volts 
off each side, This is used to run a motor-generator set and for lighting. 
Each potential transformer has 110 volts across its secondary and is used 
for relay operation. The rail return bus is connected to the rail by under- 
ground cable. One side of the secondary of e&ch r.air. transformer is connected 
to the rail return bus. One side of the primary of the o and P transformers is 
also connected to the rail return bus. 




n=n «- 


Control building 



Interlock tower with substation in "background look- 
ing south from Landover crossing 


aignal relays in interlocking tower 



In order to give a simple and dependable control of all equipment 
B.C. power is used to operate all breakers and high Bide switches. ThiB 
makes remote control possible when desirable. All auch switches and breakers 
are operated from a control board located in the control building of the 
substation. This board carries many of the relays and the control handles 
for operation of breakers and 10 tor-operated switches. A one line drawing 
of the diagram of connections is on the board in two colors, red for 1^2 KV 
lines and yellow for 12 EV lines. On these lines are placed the control 
handles in their proper positions in the circuit, With control handle 
are two lights, one green and one red. When the switch or breaker is closed 
the red light is on, when open the green light is on. The handle also has 
a lockout position in which no light shows. Thus the operator can see at a 
glance which circuits are closed and which open. 

However, to keep perfect control over an entire system of sub- 
stations such as exists in the single stretch of track from Washington to 
Baltimore, it would not be plausible to allow each substation operator to 
close and open switches without supervision. Therefore no change may be 
made in the breakers and switches of a substation without permission or 
orders for such a change from the power director's office in Baltimore. This 
office contains an enormous board on which is the diagram of all tracks and 
substations from Wilmington, Delaware to the Potomac Yards in Alexandria, 
Virginia. Every control switch over that distance is shown by a green ©r 

red light. These lights are controlled by the power director by means of 
switch buttons on a small table switchboard. The diagram is so connected 
that if any section of track has a dead trolley a series of white lights 
show on that section of the board. Thus the power director can see which 


Tower control board 


switclies may be opened or closed without cutting the pov/er on any section 
of track. In order for the substation maintainer to work on a breaker, he 
must first call the power director to get permission. If the breaker may 
be opened without interfering with the power on the trolley involved, the 
power director fives permission to open the breaker, after opening the 
breaker the maintainer calls the power director back informing him that the 
breaker is open. The power director then changes the lijht for that breaker 
from red to green. This long proceedure enables the power director to keep 
perfect control of the whole system. The substation telephone has three 
circuits for control purposes, one to the power director, one to the inter- 
locking tower, and one a PBX exchange for outside calls. 

So that it • ould not be necessary to keep a special operator in 
each substation day and nit;ht, a switchboard was placed in the nearby inter- 
locking tower which must have a man day and night to control track switches. 
This tower control board has the same circuits, control handles, and lights 
as the substation board but is much smaller because it has only two relays. 
There are six meters on the tower board. Four of these are ammeters, one for 
each main transformer. The other two are voltmeters, one for bus 24 and one 
for 25. These meters make it easier for the tower operator to compare voltages 
and currents without switching as is necessary on the station board. The two 
small lights on the board act as ground indicators for D.C. circuits when 
the switch button is pushed. The left light connects the positive side of 
the line and the right the negative. They are in series and grounded between 
them. A ground on one side would cause the light e n that side to go dead thus 
limiting the trouble to one side of the line at least. Under normal conditions 
the substation is operated from the interlocking tower under supervision of the 
power director. 


Substation Control Board 


The substation control board also contains a kilowatthaur meter. 
This meter is connected to a potential trans former on the 1?2 iry side of 
each transformer in such a way as to add up the total energy supplied to the 
substation since it began operation. In addition to that there is a voltmeter 
on the board 7/hich may be connected to either bus section 24 or 25 by turning 
a dial. This meter has a maximum of 15,000 volts, but normally reads 12,000 voltfc 

There are also two dials on the board which determine the potential 
transformer to which the relays on the board are connected. The left dial 
connects the relays on the left of the board to either P24 or P25 while the 
right dial connects the relays on the right of the board to either P24 or P25. 
ffnder normal conditions the left dial is on P24 and the right on P25, but if 
anything should happen to put one of the potential transformers out of service, 
then all the relays could be operated from the other transformer. 

On the extreme right of the switchboard there are several double 
throw knife switches. There are two panels of these, the left being a D,C», 
panel and the rirht an A.C. panel. The switches on the D.C. panel control 
groups of switches and breakers. For example one switch controls 1, 1H, 1L, and 
12 thus isolating transformer 1 completely. One double pole double throw 
switch on the D.C. panel throws the entire switch control over to the switch- 
board in the interlocking tower. When under tower control a switch handle 
turned in the substation will not operate the switch. The D.C. panel also 
contains a voltmeter which reads the voltage across the batteries. The panel 
also has ground detector lights similar to those on the tower board. 
On the A.C. panel there is a double pole, double throw switch which throws the 
motor-generator set onto either S24 or 325 as desired. Another such switch 
changes the lighting from A.C. to emergency lighting by batteries. There is 
also a switch to control an oil purifier when used and another to control the 


Baok of Substation Control Board 

mo tor-generator set. 


Tinder normal conditions the substation makes use of both 132 irv 
lines 1 and 2 without the tie between them. Therefore switches 124, 224 and 
21 are closed while 12 is open. All four transformers are normally used so 
that all "H* switches and "L" breakers are closed. The two 12 KY buses are 
usually tied together so BB is closed. ?hus the trolley buses fed from 
separate 132 KY lines are tied together. 'iThen electrification is completed 
along the freight line to Potomac Yards all JRA breakers will normally be 
closed, ^.t present, however, these trolleys, 1 and 2 south, are still being 
worked on, bo breakers 2501 and 2502 are open and the line is grounded at the 
"? M switches. All other JRAs are normally closed. Likewise 1^2 KV line 1 is 
being worked, on between Landover and Capital Substations so that switch 125 is 
open and 125G is closed. Capital is at present fed by line 2, switch 225 
being closed. Then all lines are completed 125 will also normally be closed. 

In case of troiible the several possible combinations make it 
possible to keep both 12 KV bus sections alive unless trouble arises with the 
bus Itself. If, for example, 1?2 EI jine 1 has trouble and cannot be used, 
line 2 feeds both 12 KV buses trough 2 and 2A. If it is desirable to use all 
four transformers under such conditions, that is accomplished by tying the 
high side buses together with switch 12. ?his would also allow feeding south 
on both lines if so desired. An interesting situation has already arisen in this 
connection. A kite with a tinfoil winding on it got tangled in line 2 at 
Bowie and because lines 1 and 2 were connected at Loudon Park Substation, south 
of Baltimore, every "L 1 * breaker opened from Loudon Park to Capital thus cutting 
off all the power in each substation. However, Lou&m Park was north of the 


connection "between lines and was still operating. All sectionalizing switches 
in the trolleys were closed so that Loudon Park fed all the way through to 
Washington. Since there was no heavy load on the trolleys at the time all 
trains were able to operate as usual, Kot only were the trolleys kept alive 
but all the motor-generator sets we^e kept in operation by back feed from the 
trolley to the 12 KV buses and through the service transformers which operate 
the motor-generator sets. The signal generators we^e likewise kept running 
so the signals were kept up. All substations were very quickly placed back 
in operation by disconnecting the 1^2 KV lines at Loudon Park and feeding 
through on line 1. Line 2 was kept out of operation and grounded by 224G 
until the kite string was located and removed . This presented an unusual 
circumstance which was easily met because of the thorough design of the system. 

bisect c tt t*e::t S"Pp?ly 

As was mentioned before, the control of the substation is accom- 
plished by use of a D.C. power supply. There is an excellent reason for this 
use of D.C. instead of *..C. for control. If for some reason the main power 
supply to the station is cut off, all the A.C. power is gone and there would 
be no means of controlling switches and breakers other than manually. How- 
ever with D.C. controls, the power can always be taken from batteries in case 
the A.C. is lost. The substation has sixty cells in series, each cell giving 
2 volts, making a total of 120 volts. These are Gould lead storage batteries 
and are located in a small room in the control building. The total capacity 
is about 300 ampere-hours . 

However the main D.C. supply is obtained from a motor-generator 
set which gets its nower from the service transformers. It consists of an 


Jlotor-generator set for D.C. Control 


A.C, motor rated at: 7.5 HP-110Y-75A-1450 ^PM-25 cycles A »C. -continuous duty; 
and a diverter pole D.C. generator rated at: 5EW-140V-35.7A-1450 RPM. Although 
this generator is rated at 140 Tolts it is constructed with a shunt field 
rheostat to regulate the to It age to any desired value. Although 115 to 120 
volts is all that is necessary to control the station the terminal voltage of 
the generator is usually kept about 129 volts so the Batteries which float 
on the line will be charged whil®not in use. This system keeps the batteries 
up and ready for duty in addition to supplying the necessary power for control. 
The motor is equipped with a starting coil, a no-voltage release, and a heat 
element to release the motor when overheated. The generator is equipped with 
a relay which prevents it from taking load until the voltage is sufficiently 
high and a voltmeter which reads the terminal voltage. This motor-generator 
set runs continuously unless the power is cut off or it is in need of repairs. 


It seems that the Pennsylvania Railroad authorities who had charge 
of the contracts for the substation equipment decided it would be the best 
policy to split up the contracts to the different firms as evenly as possible 
and thereby satisfy them all. Therefore in going through the substation 
equipment this will be noted. The G.E. equipment consists fflainly of switches, 
large and small transformers, and JEA high speed circuit breakers. The West- 
inghouse equipment consists mainly of the oil circuit breakers ("SB rt a nd «l m 
breakers) and the switch control boards. The Allis-Chalmers Company furnished 
large and small transformers. Relays were made by various firms. Thus the 
contracts were split quite successfully. 



All twelve switches on the high Bide of the substation are double 
pole, single throw, D.C. motor-operated 1?2 KV switches of the horn-gap type. 
These include the four line switches t 124, 224, 125, and 225, as well as the 
four ground switches, 124 G, 224G, 125G, 225G. It also includes the switches 
on the high side of each transformer, 1H, 1AH, 2H, and 2AH. Bach of the above 
twelve switches is separately motor-operated. Because of its importance in tying 
the two trolleys of the island section together, the 11 KV switch L12 had to 
be controllable from the switchboard. Therefore it was also made a motor 
operated switch* The motors are D.C. compound motorB rated at: ■^■HP-115 V-5 .6A- 
1140 ^RHlr hour duty. These motors are thrown directly across the D.C line 
from the motor-generator set when the switch control handle is turned. The 
mechanism for operating these motors contains a limit switch which automatically 
cuts off the motor when the switch reaches the desired position. Also to 
prevent a switch from only partly opening or closing a relay operates when the 
motor circuit is closed to keep it closed until the switch is fully opened 
or closed. If the switch control handle is turned while a switch id operating 
it will have no effect until operation is completed . 

The remaining switches in the subs talon are all manually operated. 
The switches isolating the "L" breakers are four pole, single throw, 11 KV 
disconnecting switches. There are four of those. There are also eleven two 
pole, single throw, 1IKV disconnecting switches, one isolating each JHA 
breaker ("B* and rt P" switches) and one isolating the "SB" breaker. In each 
of the ten trolley feeders there is a single pole, single throw, 11 KV dis- 
connecting switch ("T" switch). All service and potential transformers are 
isolated by single pole, single throw, 11 KV hook-stick operated switches, 
four such switches being necessary. This makes a total of 29 manually 


operated switches. 

All the breaker isolating switches are equipped with magnetic locks 
to prevent opening of a switch while its breaker is closed. Since the object 
of the breaker is to quench the arc when the circuit is opened it is necessary 
that the breaker always opens the circuit. If the switch opened first, the 
resulting arc on the switch would ruin it. Therefore a circuit is arranged 
such that while the breaker is closed a small plunger fits down into a hole 
preventing the turning ©f the switch operating handle. When the breaker opens 
the coil circuit of the magnetic lock closes, drawing the plunger up and per- 
mitting the operation of the switch. 


Of the four large step^-down transformers numbers 1, 2, and 2A are 
G.E. transformers, type H, form SDH, 25 cycles, single phase. They are rated! 

4500 KVA at 45 C rise for continuous duty 

S750 KVA at 60 C rise for 2 hours 

13500 KYA at 75 C rise for 5 minutes 

Voltage rating: l?2,000/l2,000 volts 

Impedance volts: average 4j£ 

Polarity:- Subtract ive 

Approx. weight to be lifted when untanking 61,000# 

Approx. weight of tank and fittings 28, 000 £ 

Approx. weight of 6470 gals. ^10C transil oil -48, 000 

Approx. total weight for outdoor installations — -l?7 f 000f? 
These transformers are also equipped with arcing horns making a shorter path 
from the top of a bushing to the horn than through the bushing for lightning. 
The gap from horn to bushing on the high voltage side is set at 47.5 inches 
and on the low voltage side at 6.25 inches. 


O.E. transformer #a with "L" breaker on rig-ht 

fnotp part of "H" switch on left) 


- ■ ;ts k 


ff.S. transformer -1 with "L" breaker 


7he other transfor^r, 1A, is art Alii s -Chalmers transformer with 
the same rating as the others. There is some difference in the weight: 

Approx. weight of core and coils 67,000'' 

Approx. weight of case and fittings 2%000# 

Approx. weight of 5470 gals, of oil 41,000" 

Approx. total weight 131,000! 

This difference in weight is mainly due to the use of 1000 less gallons of oil. 

These transformers are very similar in cou»t ruction and operation. 
They are oil filled and self-cooled. The 0*3. type are cooled by the oil 
passing through pipes on the outside. These pipes run from top to bottom and 
offer a large surface to the air, thus cooling oil in the pipes by radiation. 
The oil Oircuits slowly through the transformer proper and these pipes on the 
principle that heat rises. The Allis-Chalmera type works on the same principle 
only instead of pipes entirely surrounding it there are eight radiators placed 
in groups of two around it. A valve at the bottom of the transformer permits 
draining the oil when so desired. The large tanks on top of the transformers 
are oil reservoirs. This permits expansion and contraction of the transformer 
oil due to heat changes. On the G.E. type there is a large pipe leading up over 
the oil tank. This acts as a safety valve for it has a glass plate over the 
face of it, and a pressure on the plate would break it, thus allowing the oil 
to pass out of the transformer instead of perhaps causing internal troubles 
due to pressure. This device is on the oil tank itself on the Allis-Chalmers . 
Each transformer is equipped with a thermometer which registers internal temp- 
eratures but the scale is placed on the outside where it is easily read. The ■ 
132 T lines come into the transformers through large oil filled bushings 
which extend about four feet above the transformer. On top of the G.E. bushing 
there is a so-called "fishbowl" which is normally half full of oil. The oil 
height in the Allis-Chalmers bushing is noted by glass gauge on the top. The 


12 KV lines also come through bushings on top of the transformer, These toeing 
much smaller in size. The transformer oil must be of the very purest quality 
and must contain absolutely no water vapor for it must stand a voltage test of 
25*000 volts or more without breaking down* Each transformer has a condenser 
potential device connected to the high tension bushings. This is used for 
relay operation which will be explained later. Each transformer also has a 
set of current transformers for relay operation, consisting of two cross con- 
nected current transformers on the high tension side. 

In addition to the large power transformers there are two service 
transformers, S24 and S25. These are 50 1IVA Allis-Chalmers transforrners with 
a voltage rating of l?200/220/ll0. They carry 25 cycle, single phase A.C. and 
polarity is subtractive. The impedance is about 4%. Each uses 120 gals, of 
oil being likewise oil filled. They are small enough not to need a cooling 
system. Instead of being protected by circuit breakers, each of these trans- 
formers is fed through a small current limiting resistance and a fuse for pro- 
tection in case of trouble. This fuse is a type DLC rated at 15 a for 2300V. 
It consists of a spring coil in a liquid and a excess current flowing through 
causes it to break. The separation is rapid due to the spring tension and 
the liquid quenches any arc present. All these features make it an ideal fuse 
for its use. 

There are also two potential transformers, P24 and P25. These are 200 
volt-amperes G.E. transformers with a voltage rating of HOOO/llO. These also 
run on 25 cycles, single phase A.C. and have a subtractive polarity. These 
are much smaller than the service transformers and only contain 20 gals, of 
oil. Each of these is likewise fed through a small resistance and the same 
type of fuse, the only difference being that it is rated at -fet at 2200V. 


Oil Circuit Breakers 

All four of the H L" breakers and the "BB" breaker are Westlnghouse, 
"De-ion Grid'* oil circuit breakers. They operate with a solenoid mechanism, 
the time of opening being estimated at about one or two seconds. They are not 
called high speed though. The throwing of the switch to close this breaker 
makes up a relay closing the solenoid circuit. The solenoid draws the plunger 
down rapidly and when it reaches a certain point it closes an auxiliary switch 
which energizes a tripping coil which in turn breaks the relay contact and 
opens the solenoid circuit. This all happens before the plunger reaches the 
bottom so it traTels the remaining distance to the bottom by inertia. This 
all has the effect of reducing the force with which the plunger hits the 

bottom. When the plunger reaches the bottom it is held in this position 

against the action of two powerful/ by a latch. When this breaker is opened 

either by automatic relay operation or by the control handle a second but 

smaller solenoid is energized pulling a smaller plunger. This plunger is 

thrown up rapidly opening the contacts of the breaker. There are two contacts 

in these oil breakers each in a separate cylinder of oil. These contacts 

are pulled apart rapidly by the rising plunger, as the contacts separate, 

oil flows into the space between them thus quenching the arc. There is an 

exellent reason for using transformer breakers and bus-tie breakers that are 

■lower in action than the trolley feeder breakers. If for some reason one of 

the trolleys became short circuited the fastest breaker would operate first. 

Therefore to keep a whd©bus section from dropping out the fastest breaker is 

placed in the trolley feeder where only one trolley will be "lost". Thus the 

use of the slower operating oil breakers is an aid in keeping the trolleys 



JM treakero from under l ow structure 


Eigh Speed Circuit Breakers 

The G.E. high speed air circuit breakers, type JHA.-72, /used for 

trolley feeder protection. They operate either "by impulse trip or relay action. 
These breakers have two breaks in series consisting of two moving arms held 
in a closed position by a holding magnet and pulled away from stationary contacts 
by springs. For breaking the arc there are two arc chutes with four blowout 
magnets energized by series coils. The arc is pulled up into these asbestos 
lined chutes by the blowout magnets and is broken in air by stretching. The 
blowout coils, main contacts, and main bushing current transformers are in 
series with the circuit to be protected. Whtn the breaker is closed a small 
laminated armature fastened to the moving contact arm of the breaker bridges 
the gap of the holding magnet and thus forms a stationary pivjjt allowing the 
breaker contact springs to keep the breaker closed. A tripping coil is located 
in the gap of the holding coil magnet and in close proximity to the small arm- 
ature. A current flowing in the tripping coil in the proper direction transfers 
the flux of the holding magnet from the armature to a path through the tripping 
coil thereby releasing the armature and allowing the powerful springs to carry 
the contact arm and movable contacts rapidly back to the open position. The 
holding coil is D.C. excited. The current in the tripping coil is obtained 
during short circuit conditions by the rectifier action of the saturated core 
current transformer. The secondaries of the tripping current transformers are 
D.C. excited, and the primaries of these are connected with opposite polarity 
across the main bushing current transformer secondary. The latter is located 
on the bus side of the breaker. This arrangement produces a rectifier action 
during a sudden increase in current and circulates D.C. in the tripping coll 
in the proper direction to release the holding armature when the current reaches 
the proper value. This is called impulse trip and the breaker opens in half a 
cycle or a fiftieth of a second. 




Internal Tiew of jha breakers 
(Arc chutes at top, closing and holding 
mechanism on bottom) 




Internal view of Jfli. breakers 
(Arc chutes at top, closing ana holding 
mechanism on "bottom) 


For a gradually increasing overload the breaker is tripped through 
relay action which opens the holding coil circuit when the overload has reached 
a predetermined value. The rel^ is fed from a current transformer on the 
trolley feeder side of the "breaker. 

These breakers like the others are operated by control handles on 
the switchboard. However, these breakers are closed by a motor driven reset 
mechanism and the breaker is trip free while closing. This allows a circuit 
under load to be closed by the breaker which still affords protection against 
short circuit and overload conditions which may exist when the breaker is being 
closed. This feature is obtained by a combination of contt-ct levers with an 
arm on which the holding armature is mounted. Gears and cams are arranged 
•o that at any time during the process of setting, the mechanism is free to 
release. A magnet clutch it used to connect and disconnect the motor from 
the holding mechanism at the proper time. 

These breakers are designed for outdoor installation. They are 
covered with a weatherproof housing which is removable by parts. The breakers 
have an overall ?;ei[:ht of about 10,000 pounds. 


Perhaps the most outstanding feature of the entire substation de- 
sign is the thorough protection afforded it against any electrical disturbances 
within reason. It is so designed that it may continue operation under any 
ordinary conditions and even the most severe troubles could do but little 
damage to the station and its apparatus. 


Loofeing down on JHA. breakers 
(note "H" switch in foreground) 


Lightning Protection 

The substation has many devices for lightning protection. Even- 
tually a lightning pole of sufficient height to extend far above the highest 
substation structure will eventually be placed near the center of the station. 
The 1^2 FT lines are protected at the substation by arcing rings placed on the 
end units of insulatore. The lightning wire which runs along the top of the 
transmission poles also passes through the station. The main transformers are 
protected on both the high and low sides by arcing horns on all the bushings. 
?he 11 KV lines are protected from lightning by G.E. thyrite lightning arresters 
placed on the low steel structure and connected with the trolley feeders between 
the "P* and "T" switches. Sach trolley feeder is protected by one arrester. 

flelay Operation 

. The automatic and immediate operation of relays when bus line faults 

or overloads occur is the most important feature of substation protection. 

Nearly every possible trouble has been anticipated and relays were arranged to 

prevent damage by causing the action of some other device made for that purpose. 

The 132 KV transmission line ground protection is obtained by means 

of a type C3JV differential relay which receives its potential from condenser 

potential devices connected to the high tension condenser bushings of the 

4500 KVA transformers. This relay has two coils. One receives potential 

proportional to the line to ground voltage of one wire of the line (A phase], 

and the other coil, of the Aire of the line (3 phase). Each normally gets 

55 volts. When a ground occurs on one side of the line the voltage, on that 

side of the potential device approaches zero and the other side 110. This 

disturbs the balance of the CUV relay causing a contact arm to be drawn to 


Low structure from railroad tracks 
(note thyrite lightning arresters aboTe sign 
and signal "breaks on right) 

the strong side, This closes the "L" breaker tripping circuit causing the 
breaker to open and also drops a target in the relay to show on which wire 
the ground occurred. This is what happened in the kite string incident dis- 
cussed previously. This action takes place for every transformer. 

The 1?2 CT transmission lines are protected from short circuits 
by means of the type C3 directional control relay. This relay has a power 
directional element and also an overcurrent element which receives its current 
from a multiple tap bushing type current transformer. An AV relay receives 
potential from the bushing potential devices connected to the 4500 EVA trans- 
former. The AV voltage relay shunts out the current coils and open circuits 
the potential coil of the CH relay on normal voltage. The AT must drop out 
due to lov/ transmission line voltage and the directional element must be 
closed before the overcurrent element can start to operate. The operation 
of the CH relay closes the tripping circuit of the •L" breaker causing it 
to open. 

To protect the 4500 EVA step-down transformers against internal 
faults a type ?A ratio differential relay is used. This is energized by 
two sets of current transformers, one set consisting of two cross connected 
current transformers on the hio'h tension side of the transformer, and the 
other a similar set on the bus side of the "L H breaker. The relay has an 
operating coil and a restraining coil, there being no current flowing in 
the former under normal conditions due to a balance between the two currents 
from the two sets of current transformers. If a fault occurs in the transformer 
this balance is disturbed and the unbalanced current flows through the oper- 
ating coil causing the relay to operate. The CA relay has a front and back 
contact, the front contact being normally open, and the back contact norm- 
ally closed. If the rela; operates, the closing of the front contact 


energizes an MC auxiliary relay. A "make" contact of this relay closes the 
tripping circuit of the "L" breaker which then opens. Another "make* contact 
closes the alarm bell circuit causing it to ring. A third "make" contact 
energizes the coil of the ML lockout relay. A fourth '•make" contact forms 
a holding circuit for the MC relay until its coil is shunted out by the 
normally closed contact of the CA relay. A "break" contact opens in the 
trip circuit to the "H" BWitch, The energizing of the ML relay opens the 
closing circuit of the "L" breaker and "H" switch which cannot be closed 
again until the relay is reset by hand. The ML al*o closes a contact in the 
tripping circuit of the "H" switch which does not complete the circuit be- 
cause of the "break" contact of the MC relay. As soon as the transformer 
fault current drops below a value corresponding to the drop-out value of the 
CA relay, its back contact is again closed and shunts out the coil of the 
MC relay which becomes deenergized. The break contact Is thus closed com- 
pleting the tripping circuit of the "H" switch which then opens, isolating the 
faulty transformer from the system. Due to the above connections the "H" 
switch will not open until the fault current flowing through it is decreased 
to a safe value. 

Protection for the 11 OT buses is similar in operation to the 
faulty transformer protection. A CA-4 differential rel^y "makes up" if 
the load on the two buses differs by more than a predetermined value while 
the BB is closed. If such is the case the CA-4 is energized from multitap 
current transformers located on the side of BB away from the bus to be 

protected. '.Then the q^^ re iay "makes up" it causes the LO relay to be 

"m~de up" also. This opens the tripping circuit of every/tied to the faulty 

bus. This includes all JRA and "L" breakers as well as BB. This isolates 

that bus section ;..nd allows the other to continue in operation. The LO 

relay also opens the closing circuits to all these breakers which cannot be 

opened again until the relay is reset by hand. 


In practice, if a trolley breaker or cable feeder does not 
open in case of a particularly he^vy load, ground, or short circuit, the 
system is protected by a JD back-up relay which actuates the same LO 
auxiliary relay as the CA-4 bus differential relay after a definite time 

For protection against overload on a trolley feeder an IB-V6 
directional overeurrent, undervoltage relay is used, iai overload on the 
trolley causes a corresponding voltage drop and at a predetermined value 
the relay "makes up". This operates an instanteous auxiliary PQ relay 
which opens the holding coil circuit of the J?A breakers thus tripping 
the breaker. For long trolley sections a special distance relay type 
CEX is used in placed of the IB-V6. The IB-Y6 and CSX relays are fed from 
current transformers on the trolley feeder side of the high speed breakers. 

Preliminary Tests 

In order to insure the correct operation of all the substation 
protect ivedevices three different groups of tests were applied before the 
station was placed in operation. The first of these consisted of pre- 
liminary tests without D.C. control and power. This group consisted of: 
current transformers polarity test, primary and secondary wiring check, 
circuit breaker and transformer oil test, transformer megger test, power 
trans for-ie^ tap changing device check, manual operation of all switching 

equipment, electrical interlock check, physical check of all relays, setting 

of lightning arresters. 

The second group consisted of tests with D.C. control but no A.C 

power. These were: D.C. energizing of relay and control board, electrical 


control and indication of apparatus test, electrical interlock test, manual 
relay operation of apparatus test. 

The third group contained test with D.C. control and A.C. power. 
This included: energizing power transformer test, phase test "between 132 ffl 
lines and 11 KV buses, energizing entire substation test, redueed voltage test 
of all relay operation, full voltage test of all relay operation, phasing and 
insulation test of catenary system, directional load test. The testa for re- 
lay operation were to see if the desired results were obtained when faults of 
different kinds occured. 


In order to keep apparatus in a substation from possibly becoming 
energized due to internal faults, each piece of apparatus including all struc- 
ture work is grounded. This grounding was done by laying a 4 watt wire about a 
foot deep in clay completely around the inside of the substation. The wires 
from the structures to he grounded are 2 watt wires and are tapped onto the 
4 watt wire. The 2 watt wires are protected by treated boxes down to the clay 
to prevent the cinders from acting on the wires. 

Before any piece of apparatus may be worked on in the substation 
it must be thoroughly grounded to take the static voltage off. This is a ne- 
cessary precaution because the static voltage is sufficiently high to be very 
dangerous .This grounding is done by special grounding sticks designed for that 
purpose. They have a hook contact at one end which may be tightened by turning 
the long handle front the other end. A long insulated cable leads to a plate 
which may be fastened to a grounded structure nearby. Both leads of the ap- 
paratus should be grounded. The "G" switches in the 132 KV lines are for the 
same purpose. 


Cleaning the bushings of a ZBk breaker 
(note open position of "B" and "F M switches 

at top. AIbo note ground sticks on both sides) 



Landover Substation has very little to do with the power for signals 
which is fed over a line at £600 volts-100 cycles and is stepped down to 110 
volts at the signals. This 6600 volts is generated both at Bowie and Capital 
and Is fed both ways into Landover. Two lines oome in from Capital. These lines 
pass through 7estinghouse circuit breakers at Landover. The main line passes 
through breaker 352. This line comes in by way of Union Substation and goes 
through to Bowie. The other line from Capital passes through breaker 352A 
and is connected to Che tfnlon side of the main line. Both of these breakers 
are isolated by two pole, single throw disconnecting switches. Under normal 
conditions both of these breakers are open and the signals are fed from both 
directions. At present ^52A is not in operation because of the incomplete 
freight line. Its isolating switch is open to keep power off the breaker 
and the line being worked on* 

These signal breakers are placed in the circuit to permit a 
connection between lines in case either Bowie or Capital signal sets fail 
at any time. This connection is made automatically by the operation of re- 
lays. Two MC relays, one on each side of the breaker 352, are operated by 
current transformers on the oorres onding sides. If the power is lost on 
one side of the breaker, the KC relay on that side operates and closes the 
breaker-closing circuit. This closes the breaker and allows the power to 
feed through from the good side. Breaker 352A only has one relay because 
the other side is connected through 352. A. breaker may be reopened by a 
switch in the interlocking tower. 

Signal breaker protection when closed Is furnished by the oper- 
ation of ST, CO, and MX relays in that sequence in case of severe overloads 
due to shorts. This results in opening the breaker and locking out the clos- 


ing circuit until the IK is reset* 


Land over Substation represents one of the finest examples of modern 
electrical engineering design. It is so thoroughly protected that the most se- 
vere situations are met automatically. Its intricate apparatus is so easily con- 
trolled that an attendsnt at the station is not necessary when it is operating by 
remote control. It was designed to provide power to the trains in that section at 
all times, and this requirement is fulfilled remarkably well. 

Although it is apparently only a small part of the entire project, this 
electrical substation plays one of the most important roles in the electrification 
of the Pennsylvania Railroad.