Siemens SG8158-00 manual Blocking Capability for Breaker or Interrupter Saving

Protective Function Configuration

5

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 (1803) depends on the sec- ondary phase CT rating (1 A or 5 A) and the value is in sec- ondary amperes.

The Time Dial parameter (1805) 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 (1806) 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 (1810 and 1811) 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.

5.8Blocking Capability for Breaker or Interrupter Saving

High-set instantaneous phase overcurrent (50HS) and high- set instantaneous neutral or ground overcurrent (50HSN) functions have the capability to block 50, 51, 50N, and 51N selectively to prevent opening an interrupting device should the fault current exceed the rating of the device.

This function is used to keep an electrically-operated load break switch, recloser, or aging circuit breaker from attempt- ing to interrupt current beyond its capability or rating. It must be used in conjunction with a slight delay (25 ms) in 50 so that 50HS can pickup or trip before 50 times out and trips. Should these parameters be set, a fault large enough to cause 50HS to pickup or trip before 50 has timed out will prevent 50 and/or 51, 50N, and 51N from tripping.

50HS/N can also be matrixed to an output contact to block differential tripping of a transformer differential relay when a fault is between the interrupter and the high side (bushings) of the transformer.

Figure 5.1 Blocking Capability Diagram

5.9 Directional Phase Time Overcurrent (67)

The Directional Phase Time Overcurrent function uses a selected time overcurrent characteristic curve to determine the trip time for the applied phase currents, utilizing the volt- ages present on the VTs to determine current direction. The defined characteristic curves are valid over a range of multi- ple of pickup values. The function also includes a customer defined curve. Refer to Appendix A for detailed trip curve information. This function is only available if the voltage input option is installed.

A1900	Directional Phase Time Overcurrent (67)
Address	Parameter	Option
1901	Function	Enabled or Disabled
1902	Curve	Inverse
		Short Inverse
		Long Inverse
		Moderately Inverse
		Custom
		Very Inverse
		Extremely Inverse
		Slightly Inverse
		Definite Inverse
		I2T Without Limit
1903	Pickup	5 A CTs: 0.5-20 A or
		1 A CTs: 0.1-4 A
		(0.1 A steps)
1905	Time Dial	0.1-9.9 (0.1 steps)
1906	Filter	rms or fundamental
1907	Impedance	0-90°
1908	Direction	Forward or Reverse
1910	Freeze Wfm 1	on Pickup, on Trip, or None
1911	Freeze Wfm 2	on Pickup, on Trip, or None

24 Siemens Energy & Automation, Inc.