Low Voltage Fault Adjustment

TM 11-6130-377-14

Position the DC circuit breaker A1CB1 to ON, and

q. Install Electronic Counter AN/USM-207 to

readjust the DC variable power source to 120 vdc. The

terminals X1 and X2 of terminal board A1TB3.

cooling fans should be operating and the DC indicator

r. Position the DC and AC circuit breakers to ON

lamp should light.

and repeat the input voltage and output load variations

e. Set the Load Bank to place a 5000 watt load on

described in steps m and o. Observe that the output

the inverter. Position the AC circuit breaker A1CB2 to

frequency is 60 Hz 0.25 percent.

ON. The AC indicator lamp should light.

s. Position the DC and AC circuit breakers to OFF,

f. Readjust the DC variable power source to 115

and remove all the test equipment from the inverter

vdc.

except the variable DC power source.

g. Gradually decrease the input voltage to 94 vdc.

t. Install jumper wire between the input terminal

Verify that the DC circuit breaker trips at 95 0.5 vdc.

A1TB1-2 and the output terminal A1TB3X1.

(If this condition is not evident, perform the low voltage

u. Connect the dual trace oscilloscope with

fault adjustment procedure described in paragraph 6-

reference on A1A2C10 (A1A2C7) and one X10 probe on

23). After adjustment, set the AC and DC circuit

A1A2Q5 (A1A2Q21) collector and the second probe X10

breakers to OFF and repeat steps d, e, and f above.

on A1TB2-2. Set both inputs to 10 V/cm and horizontal

h. Gradually increase the input voltage to 143 vdc.

sweep to 5 MS/cm.

Verify that the DC circuit breaker A1CB1 trips at 142

v. Set the variable DC power source to 110 vdc

0.5 vdc. (If this condition is not evident, perform the

and position both the DC and AC circuit breakers to ON.

high voltage fault adjustment procedure described in

w. Verify that both the waveshapes shown on the

paragraph 6-24).

oscilloscope are in phase. When A1A2Q5 (A1AQ21)

i. Set the AC and DC circuit breakers OFF.

collector is high, X2 terminal of A1TB2 is also high.

Connect Distortion Analyzer TS-723/U across terminals

x. Upon completion of the functional verification

X1 and X2 of terminal board A1TB3 (fig. 2-1). Repeat

test, position the DC circuit breaker A1CB1 to OFF and

procedures in steps d, e and f above.

the AC circuit breaker A1CB2 to OFF, ensure that all

j. Repeat the procedures in step d, e, and f above.

input power is removed prior to removing the test

Verify that the output is a single-phase, 60-Hz sine wave

equipment from the unit.

with less than 5 percent distortion.

k. Position the DC circuit breaker A1CB1 to OFF,

6-23. Low Voltage Fault Adjustment

disconnect the load bank and Distortion Analyzer TS-

Adjust the low voltage trip point of the DC circuit breaker

723/U from the inverter.

A1CB1 as follows:

l. Connect Digital Voltmeter AN/GSM-64 across

a. Position the DC circuit breaker A1CB1 to OFF,

terminals X1 and X2 of terminal board A1TB1.

open front indicator panel to gain access to the inverter

m. Position the DC circuit breaker A1CB1 to ON

drive circuit board A1A2 and the DC input terminal

and the AC circuit breaker to ON. Vary the input

board A1TB1.

voltage from the DC power source between 104 vdc and

b. Pull out the plunger of the door interlock switch

141 vdc. Verify that the output voltage is 120 vac 5

A1S1 to enable the inverter to function with the front

percent.

panel open (para. 6-5).

n. Position the DC circuit breaker A1CB1 to OFF

c. Install the variable DC power source to the DC

and the AC circuit breaker A1CB2 to OFF. Leaving the

input terminal board as shown in figure 6-2.

digital voltmeter connected, reconnect the load bank to

d. Locate potentiometer A1A2R32 (A1A2R15) on

terminals X1 and X2 of terminal board A1TB3.

the inverter drive circuit board (fig. FO-3). Rotate the

o. Position the DC and AC circuit breakers to ON,

adjustment tab of the potentiometer so that it is pointing

set the load bank to 1/2 load and repeat step m. Set the

toward the transformer.

load bank to full load (5000 watts) and repeat step m.

e. Set the variable DC power source to 110 vdc

Verify that the output voltage holds at 120 vac percent

and position the DC circuit breaker A1CB1 to ON.

at all loads.

f. Lower the input voltage to 94 vdc.

p. Position the AC and DC circuit breakers to OFF,

g. Turn the adjustment tab of potentiometer

remove the digital voltmeter from the inverter.

Change 1

6-18