TECHNICAL DATA
1. Current and Time Adjustments
Earth-fault Low-set Current (I>) Adjustment
- This adjustment is for setting the minumum earth-fault
current for tripping with time delay.
- The setting range is between 0.1A to 2A
Earth-fault High-set Current (I>>) Adjustment
- This adjustment is for setting the instantaneous tripping
current due to an earth-fault.
- The setting range is between 1x to 10x of the earth-fault
low-set setting value.
I>> = a x I>
(a= 1 to 10)
- This high-set feature can be disabled by setting the
tripping current to infinity (∞).
Time Delay (TM) Adjustment
- The time multiplier is for setting the normal inverse
time/ current characteristic (IDMT) as according to
BS142.
- The setting range between 0.05 to 1.0 .
2. Light Indicators
The light indicators display the status of the system.
AUX
I>
I>>
Off
Off
Off
No auxiliary power supply.
On
Off
Off
System normal mode. No tripping.
On
Blink
Off
Earth-fault low-set start.
On
On
Off
Earth-fault low-set tripped.
On
Off
Blink
Earth-fault high-set start.
On
Off
On
Earth-fault high-set tripped.
Indicator
Status
3. Push Buttons
Reset Button
- The reset button is for resetting the light indicators (I> or I>>) after an earth-fault tripping
has occured.
- To reset, press the reset button once.
Test Button
- Test button is for checking the relay operation.
- Push and hold the test button, I> and I>> LEDs start blinking then LEDs turn On and relay
contacts will be activated after 3s.
4. Trip Contacts
There are two set of tripping contacts namely, R1 and R2.
R1,R2 - Manual Reset Type
- These contacts is activated during an earth-fault trip. The contacts remain activeted
regardless of the removal of fault current. This relay can only be reset by pressing the
“RESET” button.
N202 IDMT Earth-Fault Relay User’s Guide
AUX
I>>
I>
TEST
RESET
I
0.1A
0.5A
2A
1.5A
1A
TM
0.05
0.1
0.2
0.3
0.4 0.5 0.6 0.7
0.8
0.9
1.0
I
X1
X2
X4
X6
X8
X10
IDMT EARTH FAULT RELAY
N202
a b c
d
e
f
f
g
h
a - Low-set start/trip status indicator
b - High-set start/trip status indicator
c - Auxiliary power supply indicator
d - Test button
e - Trip reset button
f - Earth-fault low-set adjustment
g - Delay time adjustment
h - Earth-fault high-set adjustment
IDMT Normal Inverse Curve
