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ELECTRICAL
211
b) Close T,.
e) Increase reverse current
by
means of rheo-
stat R, and check that pilot lamp S glows as contacts
open.
This opening may also be unsteady: such
condition is evidenced
by
a slight buzz.
d) Check on ammeter the value of the reverse
current causing the opening of contacts: it should
not exceed 16 Amps.
e)
If
reading is unstable, or S lights up at
tolerance limit, reset reverse current to the mini-
mwn value and repeat operation e).
f)
Open switches T and T
1
and again adjust
rheostat R and potentiometer P to minimum set-
tings.
Adjusting Voltage Regulator.
(Room temperature: 1170 to 127
0
P - 47° to 53°C).
NOTE -
Regulator must be placed in oven Ap. 5014
where
it
can be maintained at above specified
temperature.
a) Wire as shown in diagram
(fig.
338).
b) Load voltage regulator setting springs by
suitably bending the relevant arm.
e)
With the unit in thermostat oven at 111° to
1270
F
(470 to 530 C) close
It
start generator and
stabilize regulator temperature by feeding current
for 30 minutes at 15 V (obtained by suitably adjust-
ing generator speed).
d) With unit still at 122
0
F (50
0
C), stop gener-
ator, open I, start generator again and speed it up
to 4,500 r.p.m.
e) Adjust voltage regulator setting spring load
by suitably bending the relevant setting arm and
by rheostat R, so
as
to have a voltage of 13.9 to
14.5 V and half-load current o( 7.5 to 8.5 Amps.
f) Check steadiness and accuracy of voltage
regulator adjustment by stopping the generator and
starting it again after a short while; then speed it
up to 4,500 r.p.m.
Adjusting Current Regulator.
(Room temperature: 1170 to 127 0 P - 47° to 53°C).
To be performed immediately after adjusting
voltage regulator, using the same wire diagram
(fig. 338) and instruments, except ammeter, which
should have a 40
A
scale.
a)
With the regulator in thermostat oven at
117
0
to 127
0
F (47
0
to 53
0
C), close I, start the gener-
ator and set its speed and rheostat R for a 13 Volt
tension and 15 to 17 Ampere output.
b) Operate in above conditions for 30 minutes
with the regulator at 111
0
to 121° F (410 to 530 C),
stop the generator and open I.
Again run the
generator at 4,500 r.p.m.
c) Adjust the load of current regulator setting
spring by bending the spring arm, and rheostat R,
in
order that regulated current and voltage are
respectively 15 to 17 Amperes and 13 Volts.
d) Check regulated current for stability and
precision by stopping generator and running it
again as hinted at b).
OPERATION TEST AND SEALING
After the regulator has been set, close the as-
sembly in a
warm
condition (see. Warning. here
below) by fitting cover and gasket, and check
as
outlined under. Bench Testing
t.
Next apply the
paint seals.
WARNING
Whenever the unit has been opened and kept
open for servicing, it must be operated for a while
and the cover fitted only after a suitable warm up
period.
Close cover carefully on
warm
unit with fixing
screws and check that rubber gasket between cover
and base is properly seated and ensures adequate
sealing.
This eliminates the moisture usually deposited on
windings and prevents the formation of moisture
occurring when cover is applied on a cold unit.
If
any moisture is trapped in the unit, during oper-
ation when the unit is warm moisture will evaporate
and deposit on armatures, thus causing highly
detrimental oxidation of contacts.
GR
,.
Fig. 338.
Wiring diagram for adJusting
voltage and
current regulators.
GR. Regulator assembly GN 2{12{16. - G. Generator
D 00{12{16/3 CS - V. Voltmeter, 20 V scale (0.5% ac·
curacy). - A. Ammeter, 15 Amp. scale (for voltage
regulator), or 40 Amp. scale (for current regu-
lator). - R. Rheostat, 25 Amps., 3 Ohms. - B. 50
Amp/hr battery, fully charged. - I. Switch.
51
L - - - - - { A } - , - - - ,
=
8
R
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