Thermistor Input Tests; Power Fail Test - GE MOTOR MANAGER 2 Instruction Manual

7.2 FUNCTIONAL TESTS
Begin testing by storing the following thermistor values:
S1 CONFIGURATION \ THERMISTOR \ HOT RESISTANCE: 30 kOHMS
S1 CONFIGURATION \ THERMISTOR \ COLD RESISTANCE: 0.1 kOHMS
S1 CONFIGURATION \ THERMISTOR \ THERMISTOR ALARM: ENABLE
S1 CONFIGURATION \ THERMISTOR \ THERMISTOR TRIP: DISABLE
Place a variable 50 K potentiometer or resistance box across thermistor terminals 17 and 18 as
shown in Figure 7–1: SECONDARY INJECTION TEST SETUP on page 7–2. With the input resis-
tance set to zero, start increasing the resistance until a thermistor alarm occurs. Verify that the Alarm
LED becomes lit and a THERMISTOR ALARM message is displayed. Use an ohmmeter to verify
that the thermistor resistance agrees with the THERMISTOR HOT setpoint value.
The thermistor will have to be removed from the MM2 to accurately measure its resistance.
When the resistance has decreased below the COLD RESISTANCE setpoint value, the alarm
will disappear.
NOTE
To check the thermistor trip function, enable the thermistor trip by making the following settings
changes:
S1 CONFIGURATION \ THERMISTOR \ THERMISTOR ALARM: DISABLE
S1 CONFIGURATION \ THERMISTOR \ THERMISTOR TRIP: ENABLE
With the thermistor resistance initially set to zero, begin increasing resistance until a thermistor trip
occurs. Note that the Tripped and Stopped LEDs are lit, the contactor A relay has de-energized, the
Running LED is off, and a THERMISTOR TRIP message is displayed. Use an ohmmeter to verify
that the thermistor resistance value agrees with the THERMISTOR HOT setpoint value. Decrease the
thermistor resistance below the THERMISTOR HOT value but not below the THERMISTOR COLD value.
Press the RESET key and verify that the MM2 still indicates a trip. Reduce thermistor resistance
below the THERMISTOR COLD value. Press the RESET key again, noting that the Tripped LED turns off
and the default display message returns. Issue a Start A command via the keypad or switch input
and note that Contactor A contacts now close and the Running LED becomes lit.
7
To test the Power Fail circuit, connect the supply voltage to the MM2 through a variac and begin
decreasing control voltage. When the control voltage drops below 80 V for 120 V AC input or 150 V
for 240 V AC input, the fault light comes on and the MM2 ceases to operate. The MM2 has insuffi-
cient voltage to continue accurately monitoring the motor. All output relays will change to their power
off state. Decrease control voltage to zero and then return voltage to its normal operating level. Verify
that the MM2 resumes its normal operation. Check the power fail memory circuit by verifying that set-
points and statistical data have not been altered.
7-6 MM2 Motor Manager 2
7 TESTING

7.2.5 THERMISTOR INPUT TESTS

7.2.6 POWER FAIL TEST

GE Power Management