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HISTORY AMD CONSTRUCTION
M ORTHERN 3UB3T AT ION
BALTIMORE TRANSIT COMPANY
A Paper Prepared as a Requirement for Initiation
TAU BETA PI
In the expansion of public utilities, the public
is generally only acquainted with that part of the service
which affects it most directly. The basic functioning of
the industry is of the greatest importance to the public
but is usually unnoticed*
The development of the street car has been made
possible , not only by research, but by developments in
economical power systems. .Public utilities are inherently
best able to serve their customers when unhampered by com-
petition; they are monopoly industries, u.'he chaotic con-
dition of city transportation in Baltimore prior to 1899
was the result of competition among the many existing lines;
the consolidation of these independent organizations into
the United Railways and Electric uompany on „aareh 4, 1899
was the beginning of one of the best transit organizations
in this country, to supply the cars with electrical ener-
gy most economically called for centralization of power
equipment; the merger made this work possible. Losses
in long cables when carrying direct current were reduced
by the use. of alternating current at high voltages, with
the subsequent conversion into direct current for the trol-
leys at substations* The final abolition of all genera-
ting plants in favor of wholesale purchase of power from
the Baltimore uonsolidated ij-as and electric Company was
to be expected in the line of increased economy.
Northern substation is not unusual; it is neither
the first substation constructed nor is it the latest; it
is not the largest plant and is not the smallest; its true
importance lies in the fact that it marked a step forward
in the development of an efficient, economical and depend-
able transit organization.
Northern substation was built on narford Avenue
at Holy Cross lane to strengthen the lines in the northern
section of the system; intended as a 4000 KW plant, the origin-
al building, now known as number one house, was completed
early in 1905 but did not begin operating under full load
until July 7, 1906. The station was found inadequate as
soon as it began operatingj and an additional building, now
known as number two house, was constructed in 1907. The
second structure was a three-walled building built upon
the north wall of the original house and in it two 1500
KW rotary converters were originally installed and operation
began in the fall of 19u7. The total capacity of the station
at this time, therefore, was 7000 KW.
Converter wo. 7, a c-000 KW unit was placed in op-
eration June 15, 1912 because of an increased load expected
from the Democratic national Convention, which convened in
Baltimore that year. An eighth unit, the largest in the
plant, having a capacity of 3000 rJi, was installed to take
care of additional increase of load in the northeastern
section of the city; this converter began operation in
To avoid power losses in the long lines leading from
Northern to the Hamilton section, it was decided to build a
semi-automatic substation in that section, in is station was
designed to be operated by one man, wording only part-time,
and capable of being removed from operation by switches at
the northern substation, This station was completed in
September, 1929; of the two rotaries installed there, one
is a &QQQ KW unit removed from northern, and the other is
a 1125 rotary removed from Uentral substation.
Thus Substation .Number 4, northern, now has a
rotary converter capacity of 10,000 tvW and operates twen-
ty-one and one half hours every day. .uever since its con-
struction has there been a total shutdown of the plant while
scheduled for operation. The continual, monotonous hum of
the converters heard by passers-by seems to indicate de-
pendability and power. "Street car service must be main-
tained" they whine.
The History and (Jonstruction of the northern Sub-
station of the rialtimore Transit Company.
Progress in industry has been so tremendous in
the past century that it is hard to comprehend the vast
amount of capital involved in the continual improvement of
methods of operation. This is especially true in those in-
dustries commonly known as public utilities, in this cate-
gory are included organizations serving the public . with
water, gas and electric supply, transportation, and com-
munication—services vital to the general populace. The
public demands dependable, economical and efficient service
from the utilities, and in order to comply with this demand,
they have continually had to expand and improve their plants.
Improvements in equipment and methods of operation have con-
tinually been utilized.
Many advancements in service have escaped the no-
tice of the public; publicity is given only to that equipment
which most closely affects the customer, many examples of this
could be cited: the streamlining of locomotives, air condi-
tioning of ears, and improvements in sleeping cars have been
widely advertised nihil e equally Important developments in
signal equipment, driving machinery, and ■ "velvet" rails
have escaped notice, oimilarly, the public has been made to
notice the new Presidents* Conference uomittee cars by wide-
spread advertisement. However, there is a great difference
in the mere passing of one of the new cars through the streets
and the extensive mechanical, supervisory, and power factors
that stand back of that car.
The history of the street car of today is more or
less well known; numerous papers have been written on the
subject. Baltimore has had a leading part in this develop-
ment; this city saw the first commercially operated electric
street car in the world make its maiden run from Oak and
Twenty-fifth otreets to the woodbury terminus on August 10,
1885. This car operated on a third rail system and the
locomotive and car are illustrated in iigure 1. The line
operating this trolley car was the iiampden branch of the
Baltimore Union Passenger uailway, a horse- car line.
In spite of the successfulness of this demon-
stration, the transit industry was still skeptical of
electric power as a means of propulsion and on May 23,
1891, the first cable-car line in Baltimore began operation
on Druid Hill Avenue. This type of road was operated by
means of an endless steel cable running on sheaves within
conduits constructed between the rails; a gripping device
held the cable at the "gripman's" will and moved the coach
forward. This car was doomed to a short life because of
numerous cable i'ractures and improvements in electrical
propulsion equipment and much capital invested in such roads
was lost. Figure 2 illustrates such a car.
To the casual observer, this history of the street
T^ird-raH Daft ipotor a^d passenger trailer
Baltimore -& Hairjpdej) Eailwa/
Irip car of typical cable liye
oar itself is a history of the transit industry; however,
the important factor of power supply nas had an important
effect on the growth of the industry. Developments in
power supply to the trolleys should be included in any
history of electrical transportation.
POWER SUPPLY DEVELOPMENT
FroflJ the time of the first electric railway line in
Baltimore to 1899 many independent lines were built in the
city, iach of these systems suppled its own power from
steam-operated generation stations located in strategic po-
sitions along the lines. The combined capacities of these
plants was greater than the maximum demand at any time of
all the lines; a single generation station of smaller capa-
city could have supplied the entire load at much greater
economy. The advantages of joint control of such an industry
soon became apparent and on March 4, 1899 a merger of all
Baltimore companies was accomplished. The new organization
was Known as the United railways and electric Company.
oince united was formed as a combination of sev-
eral independent, self-supporting companies, it possessed
numerous power plants in various parts of the city. The
wastefKUV/iess of such an arrangement soon became apparent.
United immediately began the centralization of
equipment to a central power plant with auxilliarles as needed.
The inefficiency of transmitting direct current over long
lines to outlying sections was obvious and it was decided
to generate power as alternating current in the central
station and subsequently convert this to direct current
for the trolleys in converter substations to be located
in strategic parts of th* city.
A large power plant located on .Pratt Street was
enlarged and altered to act as the central power station.
In line with the development of transmitting power as
alternating current at nif/f voltages, the first converter
substation was constructed on uruid Hill avenue in 1903,
This was followed in short order by substations at .Nun-
nery Lane and at the main generating station on Pratt
Thus in 1904, the transit system was supplied
with power as follows: Power plants at Pratt street, 15,600
KW; Light dtreet, 2,000 KW; .falls noad, 2,250 KW; Bear Creek,
675 KW; Black Kiver, 424 KW; uilmore street, 550 KW; and
Carey otreet, 600 KW, This give, a total capacity of 23,-
849 KW, The capacities of the substations were as follows:
Druid Hill, 4,500 KW; nunnery Lane, 1,500 KW; Dugan's
riharf iPratt street), 2,000 KW, Another plant owned by
United and located on uharles street was abandoned in
November, 1903 and leased to the Herald .publishing Company,
This arrangement could satisfactorily supply necessary power
for the 353 miles of track being operated, but was awkward
and unsatisfactory rrom an economic point of view.
flBGINNINaS OF JMOHTEtHM SUBSTATION
In order to eliminate several of the less effi-
cient power plants, contracts were let for two additional
substations. Eastern substation, a 3,000 K.W converter sta-
tion was completed in September, 1905 at a cost of #94-
614.64. This station was located on fifteenth otreet and
Eastern Avenue and began operating on February #7, 1906.
On June, 1905, the united railways and .electric
oompany accepted a bid from «J. nenry Miller to construct
the building for a fifth substation, to be located on j±ar-
ford rioad. The cost of the building was ^19, 764.84 and it
was completed early in 1905. This building was of red brick
construction and was designed to house four rotary con-
verter units, xhe basement wis constructed so that the passages
served as air ducts for conducting the cooling air from blower
to transformers. A balcony was provided for mounting the
high-voltage oil switches and cables leading to them in order
to keep this dangerously high voltage equipment away from em-
ployees. Ducts were built In the front wall for the emergence
of cables to the trolley structure.
The necessity for northern Substation, as the
Harford Road plant is called, was expressed in the general
manager*s report for the year 1904:
"To strengthen the lines in the northern section
of our system, a fifth substation will be constructed
in the vicinity of north Avenue and Harford Road."
The exact Bite obtained was on Jiarford Road at Holy Cross
Lane, a short distance north of North Avenue*
The contract for the electrical equipment for
the substation was taken by the General Klectric Company
with a price of $3*B„447..0P,. i'our rotary converters were
installed in the plant, iiach machine is rated at 1,000 KW
and operates at a speed of 375 revolutions per minute.
The machine is wound to operate on 25 cycle alternating current
at 430 volts and utilizes six phase power. The direct current
side of the armature is rated at 575 volts. Each rotary has
three air-cooled 375 KW General Kleotrio transformers; these
transformers step the voltage down from 13,200 as received
from the alternating current feeders to 430 volts for the
armature of the converter; each trans former is tapped at the
third points so that lower voltages for starting purposes are
available. 3ince the rotaries of this model are unable to
start themselves, each has a three-phase, 430 volt, 100 horse-
power motor mounted on the armature shaft for starting pur-
The high voltage cables feeding Northern substation
from the Pratt Street generating station were installed in
the city subway as far as North Avenue, and a twenty-four
duct subway was constructed from riorth Avenue to the sub-
station at a cost of #4, GOO, The cable for this run is a
three-conductor, oil-filled type purchased from J. A.
Roebling for a price of $25,885.
The high -volt age cable runs through ducts to the
oil switches, which, as stated before, are mounted in a
special balcony. The switches are made by the Ureneral
Electric Company and are rated at 300 amperes and 15,000
volts, since this power is three-phase, 13,200 volts and
the converters are six-phase, 430 volts, a diametrical
connection, with transformer primaries connected in delta,
is used to impose the alternating current upon the converter
armature. Diagram one illustrates this connection.
Tor cooling the transformers, air is delivered
through basement ducts at a pressure of one ounce per square
inch. This air is circulated by a Buffalo i'orge Company
twenty-five inch blower with a circulating capacity of 20,-
000 cubic feet per second; this blower is operated by a
u-eneral electric three-phase, twenty-five cycle, 350 volt,
7.5 horsepower motor which operates at 500 revolutions per
minute. The blower is illustrated in figure 3,
The station 01 is equipped with a complete switch-
ing apparatus, with indicating and measuring instruments.
A View of Rear of Station
Showing Blower in Background.
The Oil switches are Visible
in the Foreground.
notary Converter No, 1,
Capacity— 1,000 KW.
Installed July 7,1906.
Northern Substation Today; Ho. 1 House on Right.
A View of Rear of Station
Showing Blower in background.
The Oil owitches are Visible
in the Foreground.
notary Converter No. 1.
Capacity— 1,000 KW.
Installed July 7,1906.
Northern Substation Today; Ho. 1 House on Right.
Th e Instrument board consists of two sections — an alternating
current section containing relay switches for the oil s*itches
and metering devices, and a direct current section containing
switches for placing various sections of the line on the
bus bars of the station and meters for measuring the current
and power being drawn, .figures 6 f 7, and 8 illustrate the
panel board of the station*
The relays for operating the oil switches are
operated by a sixty eel}., lbO volt battery which floats
across the bus bars through suitable resistors. These
cells are of the oi-xide type,
NUMBER TWO HOUoE
■This first unit of northern substation was over-
loaded from the time it began operation and an addition be-
came essential. The report of the general manager in 1907
"As the original installation of Northern substation
was inadequate to carry the load of the sections
supplied by it, it was considered advisable to con-
struct an addition to this station, to be known as
Northern number Two, and the lot adjoining Number
One station was acquired for this purpose. "
This additional building was completed in November 1907 and
equipped with two 1500 KW rotary converters and necessary
transformers and auxiliary apparatus. An additional three-
Alternating Current Panel,
showing instruments and
relay switches for oil switches,
Direct Current Panel,
showing instruments and
switches for various lines.
Circuit breakers can he
seen above ammeters.
IJewer section of Direct uurrent Panel.
conductor high tension cable was installed from Pratt street
to this station for the purpose of talcing care of the addi-
tional load on this substation. The combined capacity of
these stations was 7000 &W and they were operated from a
single panel by a single group of operators. The station
was now capable of adequately supplying power to the entire
northeastern section of the system, including the outlying
sections of lork uoad, Towson, and uelair.
The new building was a three-walled affair built
upon the north wall of the original building. The architec-
ture of both houses is identical, number Two house was
constructed without a balcony for the oil switches to allow
the mounting of a iiiars twenty-ton crane, a machine omitted
in the original building and sorely needed. The oil switches
in the new house were mounted on the main floor..
The two rotary converters originally installed in
the new building were identical, being G-eneral Electric machines
of 1500 KW capacity, The alternating current side of the arma-
ture is designed for twenty-five cycle current at 430 volts,
while the direct current side is rated at 600 volts. The speed
of the machine is 250 revolutions per minute. Transformers
of similar make and rated at 550 KVA f with a voltage ratio
of 13,200 to 430 were installed for the converters. These
transformers are also air-cooled and tapped at the third
points for starting purposes. The converters are self -starting.
Converter No. 6.
Capacity— 1500 KW.
Installed October IS, 1907
The oil switches of No. 2 House.
300 amperes, 15000 volts.
CEKFTBALIZATION OF POWER STATIONS
After the construction of northern substation,
and the transfer of two additional units to Pratt street
generating plant from aoaxiaoned plants, it became possible
to close down the outlying plants at ^ear Creek, Preston
Street, Carey Street, ^>ilmore Street, Light Street, Fails
Road, and Owings Mills, each of which was generating current
at a cost greatly in excess tec that at Pratt Street.
The report of the general manager for 19U7 states:
"The rehabilitation of the uompany's power plants
and distributing system has made it possible to
shut down the following direct current, steam
driven power stations: G-ilmore street, Carey
Street, tiear Creek, ^ack River, and Preston Street.
From these plants the necessary equipment for the
Bay Shore power house was obtained."
Bay Shore power house was constructed in 1907 to
supply light and power to uay Shore Park since it was more
economical to build this station, using equipment from aban-
doned plants, than to run feeders from Eastern substation.
This was a 1175 Of plant, meager in comparison to the 25,000
KW capacity of Pratt Street at this time. This was the last
power plant built by united.
In 1908, the .balls Hoad plant was damaged by fire.
It was deemed advisable to close down and abandon the Jlant
as soon as cables could be run to northern substation. Thus
in 1909, the capacity of the Pratt otreet plant was £9,400 KW
and the only other station in operation was the bay Shore
power plant, used only for service during the season when the
park was open. The Owings Milla station was kept in operating
condition but unused.
Thus #ithin a period of ten years, the power supply
system of the united nailways and electric Company had changed
from a wasteful system of numerous generating plants to a
centralized power system, it then cauld be supplied with ad-
ditional hydro-electric power from the iwcCall Ferry plant of
the Pennsylvania vmter and Power Company by running high ten-
sion cables of the power company to the Pratt street plant.
The first contract for additional power was signed in 1911
when 12,000 KW were to be supplied, in that year, the united
purchased 45,174,700 kWH from the Power company, and generated
63,003,722 KWH at their fratt street plant. This amount
being supplied by the Power company was gradually increased
until the Pratt Street station was operated for emergency
service at power failures of the Pennsylvania water and Power
Company. In 1921, Consolidated u-as and JLlectrie Company,
an anillate of the Power company, purchased the Pratt street
plant and United bought all of its power from that company.
Thus United left the generation of electricity to a company
specializing in electric power supply.
LATER CHANGES AT NORTHERN 0UB0TATION
In 1911, an 125 £W booster, motor driven, formerly
used at the Falls woad power plant was placed in regular ser-
vice at Northern to boost the voltage on the line supplying
the Yowson section. This line is twelve miles long and the
booster is adjusted to boost the voltage one quarter volt
per ampere of load current. This booster set contains a
m'estinghouse lfcS &W, 265 volt, 470 ampere series generator
driven by a <<estinghouse 500 volt direct current, 250 amperes,
5b0 revolution per minute motor. (Fig. 11. )
In order to increase the capacity of northern
substation in 1912 to take care of extra demand expected on
account of the Democratic national uonvention held that year
in the city, an adaitional 2000 KW rotary converter was in-
stalled in that substation «iune 15, 1912. This Was a Jesting-
house machine, converting twenty-five cycle alternating current
at 43U volts to £75 volt direct current. The rotary operated
at a speed of 375 revolutions per minute. Three 750 KVA trans-
formers of the same make were used with the "lachine and the
diametrical method of imposing three phase current on a six
phase machine was utilized.
In 1913, city ordinances demanded the removal of
caoles from overhead structures and the switchboard at Northern
was rearranged to permit the direct current cables to leave the
building through underground ducts. The work was completed by
October 2, 1914.
By 1917, the track mileage had increased to
414.87 miles. In order to operate the new lines of rails
and to be able to supply the additional load on the system
due to increased business activity in plants manufacturing
war materials, it became necessary to further increase the
capacity of Northern substation, a 3000 KW rotary converter
with three transformers was purchased from the .vestinghouse
Electric and Manufacturing Company for a price of #36,500.
Shipment was delayed due to war conditions and the machine
was not installed until 1918. operation be&an November 30,
The ratings of this machine, the largest installed
at -orthern, called for twenty-five cycle alternating current
at 430 volts. The rotary operated at 250 revolutions per
minute and the direct current side of armature is rated at
600 volts and 500 amperes. The three transformers used with
this converter are each rated at 1125 aVA and are of the air-
cooled type, xhe high-voltage switchgear for use with this
machine was purchased from the u-eneral nilectric oompany at
a cost of |IL0,7QQ. .figures 13 and 14 show two views of this
In 1921, a plan was worked out for improving
voltage conditions on the outlying xowson and oarney sections
by using dumber i^'our converter at an eighty volt increase at
series Booster of number 1
House. Capacity — 125 KW.
number 8 Rotary Converter.
2,000 KW, 600 Volts d. c.
peak hours, The necessary additional bus structure was In-
stalled. This method of maintaining two bus-bar voltages
proved satisfactory and it was decided to make the arrange-
ment permanent. Additional bus structures were installed
and Converters ivumbenp one, two and Three were adjusted to
deliver 610 volts to the high-voltage bus. The other ma-
chines maintained the voltage on the original busses at the
normal value or 585 volts. Proper switching arrangements
made it possible to switch the tows on, ij-orsuch .avenue,
and lork woad lines to either set of busies as desired,
ihe booster could also be inserted In the Towson and i'ork
Road lines to further boost that voltage if need arose.
No important changes were made in liorthern oub-
station until the rapid development of residential areas
served by the rielair Road, Harford woad, and Carney lines
overloaded the power facilities there in 1928. Plans were
started in that year' for an additional substation in the
load eenter of that area. The site finally selected was
on rt'hite and Carter Avenues, Hamilton, Much spare capacity
was available in existing substations so it was decided to
use equipment already on hand in the new substation.
Since the new substation was in a residential
section of the city, it was decided to build it in a type
of architecture fitting for the surroundings. In order
to economize on additional operators, it was planned to make
Hamilton substation, the name given to the new plant, semi-
automatic, capable of being operated by one man working only
part lime. The estimated cost was #135,000.
The new substation was completed in 1929. It
was supplied with power by two high-tension, three-conductor
cables from .northern substation, and the two rotaries in-
stalled there were transferred from existing plants. One
of the machines, a 2QOG KW. Westinghouse machine, was moved
from Northern substation where it had been serving as num-
ber Seven converter, rhe other converter for Hamilton was
a 1125 KW machine removed from central substation.
The switchgear formerly used with the converter
while in operation at Northern was now utilised on the
high-tension cables feeding the Hamilton station. 1'hus
it became possible to take the new station out of operation
by merely opening the oil switches at northern. However,
this station can not be placed into service from remote con-
trol from the servicing station and requires an operator
for that purpose; for this reason it is considered a sem-
automatie station. The operator is present during the
peak hours of the morning and leaves the machines in opera-
tion, knowing the operators at northern will cut them out
as the load drop makes their operation unnecessary.
Some trouble developed at northern in the failure
of operators to realize when circuit breakers on the various
line s had opened until power had been off for a period of
time. Consequently, a system of signals, whereby a horn
sounds in the plant whenever any circuit breaker opens^was
From the above discussion, it is obvious that
rthern substation now has a rotary converter capacity of
10,000 KW and an additional capacity from booster sets of
£25 KW. It is served by four high-tension cables which
deliver alternating current at 13,200 volts from the Pratt
Street switching house of the consolidated Lras and Electric
Company. This company generates this current as hydro-electric
power in its stations at ^estport and Holtwood. northern
supplies power for the trolleys serving northeastern Bal-
timore; the exact lines served can be seen on Diagram 2
which shows a schematic diagram of the entire plant, in-
cluding both houses, it also relays the high voltage
power supply to a semi-automatic substation in Hamilton
and possesses the necessary oil switches ior taking this
substation out of service, Diagram is shows the exact loca-
tion of both North earn and Hamilton substations as well as
the general section of the city served.
The Baltimore iransit Company now owns and operates
Rotary Converter No. 8
Capacity— 3, 000 KW.
A view of the rear of the
direct current panel, showing
610 volt busses and feeder to
o ° o © "o o
u o u u
A schematic diagram of the layout of northern dubs tat ion showing
connections of machines, feeders, and distribution lines.
Note especially the two direct current busses, 585 and 610 volts.
^76 miles of street car track. The electrical energy con-
sumed in 1937 totaled 128,271,436 iOVH, all of which was
purchased from the Consolidated Oas, Electric Light and
Power Company. This energy in the form of alternating cur-
rent at 13,200 volts was transformed into direct current
within the thirteen substations owned and operated by the
As the street car being operated in Baltimore
grew from the rambling mechanism which maefif its initial run
on the streets of Baltimore in 1885 to the Presidents'
Conference Committee car of 1937, the equipment and method
of power supply developed also. The uneconomical production
of current in many small power stations gave way to the
central power plant system. This in turn gave way to the
use of hydro-electric power, purchased from the Consolidated
Gas, Llectric Light and j^ower uompany, thus eliminating the
capital involved in electrical production from the invest-
ment of the Baltimore Transit uompany. The present organiza-
tion whereby current is purchased at 13,200 volts, alternating
current, and transformed into 600 volts direct current in
efficient converter stations has given the residents of Bal-
timore dependable, economical transit service of both trolley
cars and coaches.
Mr. A. P. 1'rey, Electrical engineer, Baltimore Transit Go.
Mr. w. J. Guff , Superintendent of substations and Con-
struction, saltimore Transit Go.
Information and oervice department, Baltimore Transit Go.
Executive Files, Baltimore transit Go.
The Development of .teierican Street nailways , Charles DeMoss
street Ka ilw ay_s of Baltimore , united Railways and electric Co.
Files, Baltimore Sun
Files, Baltimore i^ews-Post
S, R, i>eizear, Chief iviaintainer of automatic substations,
Baltimore Transit Co.
Sir. Joe tieber, Operator, ualtimore- rransit Go.
Mr. J. t. i.ane, operator, Baltimore transit Go.