9328900990 Rev L 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 (67P, 67N, 67Q)
• Undervoltage and Overvoltage (27P and 59P)
• Auxiliary Undervoltage and Overvoltage (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:
1. The function logic must be enabled in the active logic scheme by the SL-<function> command.
2. Function inputs and outputs must be connected properly in a logic scheme.
3. 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 by eliminating compromises in coordination settings with adaptive setting groups are
endless.
Figure 4-1 shows the setting group control logic block.
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