Table 5-1. DS and GS Troubleshooting (Contd)
Test or Inspection
Test the current transformer as follows:
a. Disconnect the current transformer leads and remove the three resistors.
Never disconnect the leads of a current transformer or at a meter connected to
the transformer, when the equipment is energized. The three resistors used
with this equipment are connected across the secondary windings of the cur-
rent transformer and they ordinarily prevent an open circuit condition. But, if
a resistor were to fail and then the secondary was to be open circuited by dis-
connecting its load (the meter), extremely high voltages would be induced in
the windings. Serious damage to the equipment andd possibly the death of per-
sonnel could result.
b. Use a multimeter set on the RX1 scale and test between transformer terminals A1 and A2, B1 and B2, and
Cl and C2. Continuity should be shown all three tests.
c. Now, test between transformer terminal A1 and B1, between Al and C1. and between B1 and C1. There
should be no continuity indicated in any of these three tests.
d. Connect the meter, in turn, across the terminals of each resistor and measure the resistance. The resistance
should measure within one percent above or below 305 ohms.
If the transformer does not pass the above test, replace it. Refer to paragraph 7-5 for removal and
5. FREQUENCY METER FAILS TO INDICATE FREQUENCY
Inspect for a cracked or broken meter. Check for broken, burned, or worn wire. Test the frequency converter to de-
termine its condition as follows:
a. Model MEP-017A.
(1) Apply AC input of 120 volts, 60 hertz current across terminals marked L.
(2) With panel (M3) connected to output side meter reading should indicated 60 hertz + 0.5 hertz.
(3) For test with panel meter disconnected, direct output current of the converter shall be 100
m i c r o a m p e r
+ 10 microampere with 1100 ohm load across positive and negative terminals.
b. Model MEP-022A.
With generator set operating at 3428 rpm, remove screw in the face of the frequency
converter and adjust the potentiometer for a reading of 400 HZ on the frequency meter. If proper reading is not
obtained, proceed as follows:
(1) Disconnect the lead from the Positive (+) and negative (-) terminals on the frequency meter.
(2) Attach a multimeter with the scale set to read at least 200 microampere, to the + and terminals on the
(3) Operate generator set at 3428 rpm and turn adjusting screw to obtain a 100 microamperes on the multi-
(4) If reading is accomplished, the frequency meter on the control panel is faulty and must be replaced.
(5) If reading of 100 microamperes cannot be obtained, disconnect the wire leads from the two L terminals
on the frequency converter. Test the wire leads. If no defect is discovered, replace frequency converter and operate
generator set. Turn adjusting screw to obtain 400 HZ reading.
If frequency meter does not pass the above test, replace it. Refer to paragraph 7-2 and replace the
meter to the applicable model generator set.