Thermistor Alarm; Rtd Measurement; Power Failure / Non-Volatile Memory - GE 239 Instruction Manual

8 TESTING
1. Alter the following setpoints:
6 3527(&7,21?7(03(5$785(?7+(50,6725?7+(50,6725 )81&7,21 $/$50
6 3527(&7,21?7(03(5$785(?7+(50,6725?7+(50,6725 +27 5(6,67$1&( .:
6 3527(&7,21?7(03(5$785(?7+(50,6725?7+(50,6725 &2/' 5(6,67$1&( .:
2. As shown in Figure 8–1: SECONDARY INJECTION TEST SETUP on page 8–1, place a variable
30 kΩ resistor across thermistor terminals 21/22.
3. With the variable resistor initially 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 by the 239.
4. Remove the variable resistor and measure its resistance with an ohmmeter to verify that it
agrees with the 6 3527(&7,21?7(03(5$785(?7+(50,6725?+27 5(6,67$1&( setpoint.
5. Place the variable resistor back on terminals 21 and 22 and start decreasing its resistance until
the thermistor alarm disappears. This will occur when the input resistance has decreased below
the 6 3527(&7,21?7(03(5$785(?7+(50,6725?&2/' 5(6,67$1&( setpoint.
6. Once again, check by removing the variable resistor and measuring its resistance by putting an
ohmmeter across its terminals to verify that it agrees with the 6 3527(&7,21?7(03(5$785(?7+(5
0,6725?&2/' 5(6,67$1&( setpoint.
1. Alter the following setpoints:
6 3527(&7,21?7(03(5$785(?57' ?57'  7<3( 37
6 3527(&7,21?7(03(5$785(?57' ?57'  $33/,&$7,21 %($5,1*
6 3527(&7,21?7(03(5$785(?57' ?57'  75,3 7(03(5$785( 2))
6 3527(&7,21?7(03(5$785(?57' ?57'  $/$50 7(03(5$785( 2))
2. To verify RTD 1 readings ensure a 10 turn 200 Ω variable resistor is connected to terminals 49,
50 and 51 as shown in Figure 8–1: SECONDARY INJECTION TEST SETUP on page 8–1.
3. Using Table 4–3: RTD RESISTANCE VS. TEMPERATURE on page 4–32 as a reference, input
various resistances and verify that displayed temperatures in $ 0(7(5,1*?7(03(5$785(?%($5,1*
57'  7(03(5$785( match the results shown in the Resistance vs. Temperature table.
4. Repeat the above steps with RTD 2 and RTD 3 inputs.
1. Slowly decrease the AC voltage applied to a 239 relay until the UNDERVOLTAGE message
appears on the 239 display. At this instant all output relays will go to their de-energized state and
the SERVICE LED turns on. This phenomenon should occur after the voltage has decreased
below 70 V.
2. To test the memory circuitry of the relay, remove and then re-apply control power. All stored set-
points and statistical data should be unchanged. The displayed thermal capacity in $ 0(7(5
,1*?02725 &$3$&,7< will continue to decrease even when control power is removed. An accurate
value of thermal capacity is guaranteed if the power off time is less than 60 minutes.
GE Multilin
Courtesy of NationalSwitchgear.com

8.12 POWER FAILURE / NON-VOLATILE MEMORY

239 Motor Protection Relay
8 TESTING

8.10 THERMISTOR ALARM

8.11 RTD MEASUREMENT

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