BE1-951
Protection and Control
4-1
SECTION 4 • PROTECTION AND CONTROL
INTRODUCTION
The BE1-951 provides many functions that can be used to protect and control power system equipment in
and around a protected zone.
BE1-951 protection functions include:
Instantaneous Overcurrent with Settable Time Delay (50TP, 50TN, 50TQ, 150TP, 150TN, 150TQ)
Time-Overcurrent (51P, 51N, 151N, 51Q)
Voltage Restraint for 51P Phase Time Overcurrent (27R)
Directional Control Element(67P, 67N, 67Q)
Undervoltage and Overvoltage (27P and 59P)
Auxiliary Undervoltage and Over voltage(27X and 59X/159X)
Negative Sequence Overvoltage (47)
Directional Power (32)
Overfrequency and Underfrequency (81, 181, 281, 381, 481, 581)
Breaker Failure (BF)
VT Fuse Loss Detection (60FL)
General Purpose Logic Timers (62, 162)
Overexcitation, Volts per Hertz (24)
Sync-check (25)
BE1-951 control functions include:
Four-shot recloser (79) with zone sequence coordination, sequence controlled blocking, and reclose
control of setting group.
Virtual Selector Switches (43, 143, 243, 343)
Virtual Breaker Control Switch (101)
Virtual Lockout Protection (86, 186)
Four setting groups allow coordination to be adapted for changes in operating conditions. Setting groups
can be selected using programmable logic criteria.
Using Protection and Control Functions
Three steps must be taken before using a protection or control function.
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The function logic must be enabled in the active logic scheme by the SL-<function> command.
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Function inputs and outputs must be connected properly in a logic scheme.
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Function characteristics or settings must be programmed and based on the specific application
requirements.
If a preprogrammed logic scheme is used in a typical application, items 1 and 2 may be skipped. Most
preprogrammed schemes are general in nature. Unneeded capabilities can be disabled by a setting of zero.
For example, if the second neutral time overcurrent function is enabled but not needed, disable it by setting
the 151N pickup setting at zero (S#-151N=0,0,0).
More information about the individual function logic of item 1 is provided in this section. Information
pertaining to items 2 and 3 is available in Section 7,
BESTlogic Programmable Logic and Section 8,
Application.
SETTING GROUPS
The BE1-951 provides a normal setting group(SG0) and three auxiliary setting groups (SG1, SG2, and SG3).
Auxiliary setting groups allow adapting the coordination settings to optimize them for a predictable situation.
Sensitivity and time coordination settings can be adjusted to optimize sensitivity or clearing time based upon
source conditions or to improve security during overload conditions. The possibilities for improving protection
