BE1-951
Protection and Control
4-57
virtual switch can be operated both locally from the HMI and remotely from a substation computer or modem
connection to an operator’s console.
The breaker control switch emulates a typical breaker control switch with a momentary close, spring return,
trip contact (output 101T), a momentary close, spring return, close contact (output 101C), and a slip contact
(output 101SC). The slip contact output retains the status of the last control action. That is it is FALSE (open)
in the after-trip state and TRUE (closed) in the after-close state. Figure 4-39 shows the state of the 101SC
logic output with respect to the state of the 101T and 101C outputs.
When the virtual control switch is controlled to trip, the 101T output pulses TRUE (closed) for approximately
200 milliseconds and the 101SC output goes FALSE (open). When the virtual control switch is controlled
to close, the 101SC output pulses TRUE (closed). The status of the slip contact output is saved to
nonvolatile memory so that the relay will power up with the contact in the same state as when the relay was
powered down.
BESTlogic Settings for 101 Virtual Breaker Control Switch
Virtual selector switch logic settings enable the 101 element by selecting the mode of operation. These logic
settings are listed in Table 5-44. There are no logic inputs. The user label for the 101 virtual breaker control
switch is entered using the SB-LOGIC command. More information about the SB-LOGIC command is
provided in Section 6,
Reporting and Alarms Functions, Breaker Monitoring.
Table 4-44. 101 Virtual Selector Switch BESTlogic Settings
Function
Range/Purpose
Default
Logic Mode
0 = Disabled, 1 = On/Off
0
BESTlogic settings for the 101 function are made through the ASCII command interface using the SL-101
(settings logic-101 switch) command.
SL-101 Command
Purpose:
Read or set the logic for virtual breaker switch 101.
Syntax:
SL-101[=mode]
SL-101 Command Example
1.
Read the 101 logic.
>SL-101
1
The returned setting indicates that the 101 element is enabled.
Select Before Operate Control of Virtual Breaker Control Switch
The state of each virtual selector switch can be controlled at the HMI through screen 2.2.1. Control is also
possible through the ASCII command interface by using the select-before-operate commands CS-101
(control select-virtual control switch) and CO-101 (control operate-virtual controls switch). A state change
takes place immediately without having to execute an exit-save settings command.
CS/CO-101Command
Purpose:
Select and operate the virtual control switch.
Syntax:
CS/CO-101[=<action>]
Comments: action = T to pulse the 101T output, C to pulse the 101C output
The virtual switch control commands require the use of select-before-operate logic. First, the command must
be selected using the CS-101 command. After the select command is entered, there is a 30 second window
during which the CO-101 control command will be accepted. The control selected and the operation selected
must match exactly or the operate command will be blocked. If the operate command is blocked, and error
message is output.
