Ground Current Accuracy; Ground Alarm And Trip - GE 239 Instruction Manual

8 TESTING
1. Alter the following setpoints:
6 6<67(0 6(783?&7 ,13876?*5281' 6(16,1* ; 
6 6<67(0 6(783?&7 ,13876?*5281' &7 35,0$5< 
6 3527(&7,21?*5281' &855(17?*5281' 75,3 2))
6 3527(&7,21?*5281' &855(17?*5281' $/$50 2))
2. To determine if the relay is reading the proper ground current, inject various ground currents
shown in the table below into the 5A ground input and view the readings in $ 0(7(5,1*?&85
5(17?*5281' &855(17 and verify with the expected readings stated in the table.
Table 8–4: GROUND CURRENT ACCURACY TEST
INJECTED EXPECTED GROUND
CURRENT CURRENT READING †
0.5
1.0
3.5
5.0
6.0
†
displayed current
1. Alter the following setpoints:
6 6<67(0 6(783?&7 ,13876?*5281' 6(16,1* 5(6,'8$/
6 6<67(0 6(783?&7 ,13876?3+$6( &7 35,0$5< 
6 3527(&7,21?*5281' &855(17?*5281' 75,3 75,3
6 3527(&7,21?*5281' &855(17?*5281' 35,0$5< 75,3 3,&.83 
6 3527(&7,21?*5281' &855(17?*5281' $/$50 020(17$5<
6 3527(&7,21?*5281' &855(17?*5281' 35,0$5< $/$50 3,&.83 
2. While viewing $ 0(7(5,1*?&855(17?*5281' &855(17 , begin injecting current into the 5A ground
input. The ALARM LED will become lit and the alarm relay will change state at one half the trip
setting; i.e. at a displayed Ground Fault current of 40 A (40% of 3+$6( &7 35,0$5< setting).
3. With the display showing GROUND ALARM message, change the display to $ 0(7(5,1*? &85
5(17?*5281' &855(17 and continue increasing the input current. When the display current of 80
A (80% of 3+$6( &7 35,0$5< ) is reached, the 239 trip relay will activate and the TRIP LED will
become lit. The 239 will display CAUSE OF LAST TRIP: GROUND FAULT message.
4. Turn the ground current off and press the reset key to reset the trip relay.
GE Multilin
Courtesy of NationalSwitchgear.com
ACTUAL GROUND
CURRENT READING
10
20
70
100
120

PHASE CT PRIMARY
×
injected current ---------------------------------------------------------- -
=

239 Motor Protection Relay

8.6 GROUND CURRENT ACCURACY



5 A

8.7 GROUND ALARM AND TRIP

8 TESTING
8
8-5