BE1-951
Application
8-3
are designated to specific function blocks. OUT2 operates for instantaneous phase overcurrent conditions,
OUT3 trips for timed phase overcurrent situations, OUT4 operates for instantaneous neutral and negative
sequence overcurrent conditions, and OUT5 operates for timed neutral and negative sequence overcurrent
conditions.
All contact sensing inputs are unassigned, but IN1 is typically assigned to monitor breaker status (52b).
Inputs IN2, IN3, and IN4 are available for user specified functions.
Voltage protection, frequency protection, automatic reclosing, breaker failure, breaker control, and virtual
switches are not included in this logic scheme.
Operation - Setting Group Selection
A setting group can be selected automatically or by using the communication ports or the front panel HMI.
Automatic setting group changes are based on current level and duration. Automatic setting group changes
for cold load pickup and/or dynamic setting adjustments are enabled by the SP-GROUP# command. Setting
group changes initiated by contact sensing inputs are not accommodated in this scheme, but IN2, IN3, or
IN4 can be programmed to provide this function.
Operation - Alarms
If the continuous self-test diagnostics of the relay detect an error, failsafe output contact OUTA will close and
the Relay Trouble LED of the HMI will light. OUTA will also close if relay operating power is lost. More
information about alarms is provided in Section 6,
Reporting and Alarm Functions.
Table 8-1. BASIC-OC Contact Sensing Input Logic
Input
Purpose
Variable Label
State Labels
Closed (1)
Open (0)
IN1
Optional input used for breaker status indication in
Sequence of Events Reporting. TRUE when breaker
is open. Typically, IN1 is connected to the 52b contact
of the breaker.
BREAKER
OPEN
CLOSED
IN2
Not used
INPUT_2
CLOSED
OPEN
IN3
Not used
INPUT_3
CLOSED
OPEN
IN4
Not used
INPUT_4
CLOSED
OPEN
Table 8-2. BASIC-OC Function Blocks Logic
Function
Purpose
BESTlogic
Expression
Mode Setting
50TP
Used for instantaneous phase overcurrent protection
0
1 (enabled)
50TN
Used for instantaneous neutral overcurrent protection.
0
1 (3-Phase
Residual)
50TQ
Used for instantaneous negative sequence overcurrent
protection.
0
1 (enabled)
150TP
None
0
0 (disabled)
150TN
None
0
0 (disabled)
150TQ
None
0
0 (disabled)
51P
Used for timed phase-overcurrent protection.
0
1 (enabled)
51N
Used for timed neutral-overcurrent protection.
0
1 (3-Phase
Residual)