SINGLE-PHASE COMMUTATOR MOTORS
Commutation Constant:

393

1 +

—— 1 _

(57)

Or, denoting:

substituting (32) and expanding:

_ 0 {1 -Co [/Sa" + (1 - Ł2) a'J-

-/ff — ~........ • ......."

x"4-Sa']!

ZD

e{l-co(8a

L-,S2)a"4-Sa']}

(58)

(59)

and, absolute:

L - S2) Ť"4 - Sa'}2

-Vs1

- co[5a" + (1 - S2) a'4]}2 + Co2 {(1 - S2) a"4 - Sa'}2

(1 - -Scoa")2 +

(61)

Perfect commutation, or /„ = 0, would require from equation

(58):

1 - ct[8a?r+ (l-<S2)a'4] = 0,
.(1 - S2) a"4- Sa' = 0;
or:

(62)

1 -

sŤ' i

4 = 1 _ g2 = 1 — Ť 4-

(63)

This condition can usually not be fulfilled.
The commutation is best for that speed, S, when the commu-
tation current, ia, is a minimum, that is:

0-

U)

hence:

(64)