Basler Electric BE1-79A 9310200114 - Manual (Page 51)

APPENDIX A
• RS CONTACT APPLICATION
Introduction
The RS contact can be applied to disable the instantaneous trip circuit of protection relays after any close
attempt, typically leaving only time overcurrent protection in service. It can also be used to block
transformer load tap changer (LTC) changes during a reclosing sequence. For transmission line
applications, it has been used to permit operation of other automatic devices such as motor operated
switches in line sectionalizing operations.
RS Contact Output State
To illustrate RS contact operation, Table A-1 lists the possible setting combinations for SP-79ARS
command mode (D or E). RS is a normally closed contact.
Table A-1. RS Contact Operation Table
SP-79ARS
Command
Parameters
RS Contact State When:
BE1-79A
Power Off
BE1-79A
Reset Applied Removed
D,0,145 Closed Closed Opens as soon as 52b makes Closes at 145 s
D,2.5,145 Closed Closed Opens at 2.5 s Closes at 145 s
E,0,145 Closed Open Closes as soon as 52b makes Opens at 145 s
E,2.5,145 Closed Open Closes at 2.5 s Opens at 145 s
Table A-1 Notes
SP-79ARS command syntax is SP-79ARS[=,,]. Mode D indicates that
the RS element is de-energized or “dropped out” when power is applied to BE1-79A terminals 2 and 8.
Mode E indicates that the RS element is energized or picked up when power is applied to BE1-79A
terminals 5 and 6.
In Applied mode, the RS contact functions opposite of the way it does in Removed mode and BE1-79A
Power Off mode.
When the ac or dc operating power applied to terminals 5 and 6 is interrupted during a reclose sequence,
the RS contact returns to the close state.
The mode of the RS contact offers the ability to invert the relay logic. In D (de-energized) mode, the
position of the RS contact will follow the classic definition of relay logic:
•
If RS logic is 0, the RS relay coil is de-energized.
•
If RS logic is 1, the RS relay coil is energized.
In E (energized) mode, the relay logic is inverted and the RS coil is normally energized and then de-
energized when the RS logic goes to 1. The effect is:
•
If RS logic is 0, the RS relay coil is energized.
•
If RS logic is 1, the RS relay coil is de-energized.
Note that if E logic is selected and the relay RS logic is 0, the RS coil will be energized and holding the
output contact against its internal spring. However, if the relay loses power at this point, the RS contact
will change to the close state. Table A-1 is based on these explanations and will be referred to throughout
the remainder of this appendix.
9310200893 Rev C BE1-79A RS Contact Application A-1