Siemens SG8158-00 manual Phase Time Overcurrent, Neutral Time Overcurrent 51N

Protective Function Configuration

5.6 Phase Time Overcurrent (51)

The Phase Time Overcurrent function uses a selected time overcurrent characteristic curve to determine the trip time for the applied phase currents. The defined characteristic curves are valid over a range of multiple of pickup values. The func- tion also includes the ability to select a customer defined curve. This function is always enabled. Refer to Appendix A for detailed trip curve information.

A1700	Phase Time Overvurrent (51)
Address	Parameter	Option
1702	Curve	Inverse
		Short Inverse
		Long Inverse
		Moderately Inverse
		Custom
		Very Inverse
		Extremely Inverse
		Definite Inverse
		Slightly Inverse
		I2T Without Limit
1703	Pickup	5 A CTs: 0.5-20 A or
		1 A CTs: 0.1-4 A
		(0.1 A steps)
1705	Time Dial	0.1-9.9 (0.1 steps)
1706	Filter	rms or fundamental
1709	Reset	Instantaneous or Disk Emulation
1710	Freeze Wfm1	on Pickup, on Trip, or None
1711	Freeze Wfm2	on Pickup, on Trip, or None
1712	Blocked by	None, 50HS, 50HSN, or
		50HS & 50 HSN

The Curve parameter (1702) allows the selection of the pre- programmed characteristic curve used by this function. The ISGS relay comes with nine standard and one custom over- current characteristic curves that can be adjusted with the Time Dial parameter. The custom curve is a user-definable protective curve that integrates with instantaneous reset. The lower limit of the custom curve is 1.10. The maximum time to trip is the time at 1.10.

The range of the pickup value (1703) depends on the sec- ondary phase CT rating (1 A or 5 A) and the value is in sec- ondary amperes. The function begins timing when any individual phase current exceeds the pickup current setting.

Note: The pickup point is 1.06 of the pickup set- ting. Refer also to paragraph on Pickup in Section 5.1.

The Time Dial parameter (1705) used for the selected curve allows the time-to-trip of the curve to be raised or lowered The dial can be adjusted from 0.1 to 9.9 in steps of 0.1.

The Filter parameter (1706) sets the sensing method used by the function in its pickup calculations. The rms filter uses fun- damental current plus harmonics, while the fundamental filter ignores harmonics.

The Reset parameter (1709) offers instantaneous or disk emulation settings. Selecting Instantaneous causes the relay to clear the timer when the current drops below the pickup threshold. Selecting Disk Emulation causes the relay to simu- late the integrating disk characteristics of electromechanical relays, where the delay time decays over time. With disk emulation, a relay that continuously picks up and drops out will eventually trip. Set this parameter to Instantaneous when using a custom curve.

Each of the two waveform capture buffers (1710 and 1711) can be independently programmed to freeze snapshots on pickup or trip.

The function is able to actuate any binary output contact on pickup, and any trip or binary output contact on trip.

5.7 Neutral Time Overcurrent (51N)

The Neutral Time Overcurrent function uses a selected time overcurrent characteristic curve to determine the trip time for the applied current at the fourth current input. The defined characteristic curves are valid over a range of multiple of pickup values. The function also includes a customer defined curve. Refer to Appendix A for detailed trip curve informa- tion.

A1800	Neutral Time Overcurrent (51N)
Address	Parameter	Option
1801	Function	Enabled or Disabled
1802	Curve	Inverse
		Short Inverse
		Long Inverse
		Moderately Inverse
		Custom
		Very Inverse
		Extremely Inverse
		Definite Inverse
		Slightly Inverse
		I2T Without Limit
1803	Pickup	5 A CTs: 0.5-20 A or
		1 A CTs: 0.1-4 A
		(0.1 A steps)
1805	Time Dial	0.1-9.9 (0.1 steps)
1806	Filter	rms or fundamental
1809	Reset	Instantaneous or Disk Emulation
1810	Freeze Wfm1	on Pickup, on Trip, or None
1811	Freeze Wfm2	on Pickup, on Trip, or None
1812	Blocked by	None, 50HS, 50HSN, or
		50HS & 50 HSN

The Neutral or Ground Time Overcurrent function can be enabled and disabled (1801).

The Curve parameter (1702) allows the selection of the pre- programmed characteristic curve used by this function. The ISGS relay comes with nine standard and one custom over- current characteristic curves that can be adjusted with the Time Dial parameter. The custom curve is a user-definable

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