Ground-Fault Protection

Presentation

Ground-fault protection on MicroLogic 6 E-M trip units protects all types of motor applications against ground-fault currents in the TN-S system. For more details, refer to DOCA0187•• ComPacT NSX - Circuit Breakers and Switch-Disconnectors 100–630 A - User Guide.

Operating Principle

Ground-fault protection is definite time. It can be configured as Ig pickup and as tg trip time delay.

Tripping curve:

The ground-fault protection parameters are:

A: In Trip unit setting range
G: Ig Ground-fault protection pick-up
H: tg Ground-fault protection time delay

Setting the Ground-Fault Protection

Set the Ig pickup:

With the MicroLogic trip unit Ig dial to preset the value and the keypad to fine-tune the value
With EcoStruxure Power Commission software (password-protected)
By sending a setting command using the communication network (password-protected)

Set the tg time delay:

With the keypad on the MicroLogic trip unit
With EcoStruxure Power Commission software (password-protected)
By sending a setting command using the communication network (password-protected)

Ig Pickup Setting Values

The Ig pickup setting value is in multiples of In.

The default Ig pickup setting value is the same as the minimum dial value:

0.60 In for trip units rated 25 A
0.30 In for trip units rated 50 A
0.20 In for trip units rated > 50 A

Ground-fault protection can be deactivated by setting the Ig dial to the OFF position.

Ground-fault protection can be reactivated even with the Ig dial in the OFF position:

By fine-tuning on the keypad
With EcoStruxure Power Commission software (password-protected)
By sending a setting command using the communication network (password-protected)

The following three tables specify the setting values (preset by a dial) and setting ranges (set on the keypad):

For trip units rated 25 A
For trip units rated 50 A
For trip units rated > 50 A

On the keypad, the increment is 0.05 x In.

Rating 25 A

Type of setting	Value or setting range (x In)
Preset by a dial	0.60	0.60	0.60	0.60	0.70	0.80	0.90	1	OFF
Setting range on the keypad	0.60	0.60	0.60	0.60	0.6–0.7	0.6–0.8	0.6–0.9	0.6–1	0.6–1 + OFF

Rating 50 A

Type of setting	Value or setting range (x In)
Preset by a dial	0.30	0.40	0.50	0.60	0.70	0.80	0.90	1	OFF
Setting range on the keypad	0.30	0.3–0.4	0.3–0.5	0.3–0.6	0.3–0.7	0.3–0.8	0.3–0.9	0.3–1	0.3–1 + OFF

Rating > 50 A

Type of setting	Value or setting range (x In)
Preset by a dial	0.20	0.30	0.40	0.50	0.60	0.70	0.80	1	OFF
Setting range on the keypad	0.20	0.2–0.3	0.2–0.4	0.2–0.5	0.2–0.6	0.2–0.7	0.2–0.8	0.2–1	0.2–1 + OFF

The accuracy range is +/-10%.

tg Time Delay Setting Values

The tg time delay setting value is in seconds. The hold and breaking times are in milliseconds.

The default tg time delay setting is 0 s.

The following table shows tg setting values in second (s) and the associated hold and breaking times in milliseconds (ms):

Function	Value
tg (s)	0	0.1	0.2	0.3	0.4
Hold time (ms)	20	80	140	230	350
Maximum breaking time (ms)	80	140	200	320	500

Testing the Ground-Fault Protection

The ground-fault protection can be tested to check the electronic tripping function of the trip unit. Use the keypad of the MicroLogic 6 trip unit to perform this test.

The ground-fault protection test can be performed with the padlock locked or unlocked .

Follow these steps to test and reset the ground-fault protection on MicroLogic 6 trip units.

Step	Action	Display
1	Provide a power supply to the trip unit so that the screen displays the result of the test after the circuit breaker trips.	–
2	Select the Instantaneous measurement readout mode (the display is the most heavily loaded phase, in this example Phase 2).
3	Select the ground-fault current measurement screen (the value is a percentage of the Ig setting).
4	Access the ground-fault protection test function by pressing OK. The tESt pictogram appears and the OK pictogram blinks.
5	Prompt the ground-fault protection test by pressing OK. The circuit breaker trips. The ground-fault protection trip screen is displayed.
6	Acknowledge the ground-fault trip screen by pressing OK. The Reset? OK pictogram blinks.
7	Confirm by pressing OK again. The confirmation OK is displayed for 2 s.