Ground-Fault Alarm (ANSI 51N/51G)
The ground-fault alarm and earth-leakage alarm functions operate as ground-fault and earth-leakage protections, using the same sensors. They are independent from these protections and have their own settings.
The ground-fault alarm is based either on the summation of the phases and neutral current or on the signal delivered by an external sensor, source ground return (SGR) current transformer through the MDGF module.
The earth-leakage alarm function is a residual current alarm based on the current measured by a rectangular sensor encompassing the three phases or the three phases and the neutral.
The ground-fault alarm function is available when the ANSI 51N/51G Ground-fault alarm Digital Module is purchased and installed on the MicroLogic control unit.
The ground-fault alarm function is powered by the current flowing through the internal current transformers of the circuit breaker and it does not require an additional external power supply.
The ground-fault alarm function is compatible with:
o3-pole and 4-pole circuit breakers
oMicroLogic 2.0 X, 5.0 X, 6.0 X, and 7.0 X control units for IEC standard
oMicroLogic 3.0 X, 5.0 X, and 6.0 X control units for UL standard
oMicroLogic X control units with firmware version greater than or equal to 002.000.002. Earlier firmware versions need to be updated.
Data from the Digital Module is available remotely through IFE/EIFE or IFM communication interfaces, if the IFE/EIFE or IFM firmware version is compatible with the Digital Module. For more information, refer to firmware compatibility of the communication interfaces.
NOTE: When installed on a MicroLogic 7.0 X control unit, the ANSI 51N/51G Ground-fault Alarm Digital Module activates the earth-leakage alarm.
External sensors can be used:
oExternal Neutral Current Transformer (ENCT): measurement of the current on neutral. For information about the installation of ENCT, consult the instruction sheet on the Schneider Electric website: NHA14388.
oSource ground return protection: including ground-fault protection and an SGR sensor installed around the connection of the transformer neutral point to ground. For information about the installation of the SGR sensor, consult the instruction sheet on the Schneider Electric website: NHA92405.
oExternal rectangular sensor: measurement of the residual current. For information about the installation of the external rectangular sensor, consult the instruction sheet on the Schneider Electric website: NVE35468.
Ground-fault alarm operates in the same way as ground-fault protection, except that an alarm is generated instead of a trip.
The ground-fault alarm settings for MicroLogic 2.0 X, 3.0 X, 5.0 X, and 6.0 X are:
oIg alarm mode: enables or disables ground-fault alarm
oIg alarm: ground-fault alarm threshold
otg alarm: ground-fault alarm time delay
The earth-leakage alarm settings for MicroLogic 7.0 X for IEC Standard are:
oIΔn alarm mode: enables or disables earth-leakage alarm
oIΔn alarm: earth-leakage alarm threshold
oΔt alarm: earth-leakage alarm time delay
They can be set as follows:
oWith EcoStruxure Power Commission software (password-protected)
oWith EcoStruxure Power Device app (password-protected)
The dual settings function does not apply to the ground-fault alarm function. When the dual settings function is enabled, ground-fault alarm settings are the same whether set A or set B settings are activated.
Ground-fault alarm settings on MicroLogic 2.0 X, 5.0 X, and 6.0 X IEC standard:
|
Setting |
Unit |
Range |
Step |
Factory setting |
Accuracy |
|---|---|---|---|---|---|
|
Ig alarm mode |
– |
ON/OFF |
– |
OFF |
– |
|
Ig alarm |
A |
0.2–1 x In |
1 |
0.2 x In |
±10% |
|
tg alarm |
s |
1–10 |
0.1 |
1 |
±500 ms |
Ground-fault alarm settings on MicroLogic 3.0 X, 5.0 X, and 6.0 X UL standard:
|
Setting |
Unit |
Range |
Step |
Factory setting |
Accuracy |
|---|---|---|---|---|---|
|
Ig alarm mode |
– |
ON/OFF |
– |
OFF |
– |
|
Ig alarm |
A |
120–1200 |
1 |
120 |
±10% |
|
tg alarm |
s |
1–10 |
0.1 |
1 |
±500 ms |
Earth-leakage alarm settings on MicroLogic 7.0 X IEC standard
|
Setting |
Unit |
Range |
Step |
Factory setting |
Accuracy |
|---|---|---|---|---|---|
|
IΔn alarm mode |
– |
ON/OFF |
– |
OFF |
– |
|
IΔn alarm |
A |
0.5–22 |
0.1 |
0.5 |
Complies with IEC 60947-2 Annex B |
|
Δt alarm |
s |
1–10 |
0.1 |
1 |
±2% |
NOTE: In order to differentiate between earth-leakage alarm and earth-leakage fault, it is recommended to set the earth-leakage alarm threshold below 75% of the earth-leakage fault threshold.
The function generates the following predefined event for MicroLogic 2.0 X, 3.0 X, 5.0 X, and 6.0 X control units:
|
Code |
Event |
History |
Severity |
|---|---|---|---|
|
0x050C (1292) |
Ig alarm |
Protection |
Medium |
The Ig alarm event is not generated when the Ig alarm mode is OFF.
The function generates the following predefined event for MicroLogic 7.0 X control units:
|
Code |
Event |
History |
Severity |
|---|---|---|---|
|
0x050D (1293) |
IΔn alarm |
Protection |
Medium |
The IΔn alarm event is not generated when the IΔn alarm mode is OFF.
Predefined events cannot be modified by the user. For general information about events, refer to Event management.
|
Code |
Event |
Recommended actions |
|---|---|---|
|
0x050C (1292) |
Ig alarm |
Check insulation between phase/neutral and ground (earth). |
|
0x050D (1293) |
IΔn alarm |
Check insulation between phase/neutral and ground (earth). |
