BE1-951
General Information
1-3
With the optional auxiliary voltage input connected to the bus, one sync-check function provides synchronism
protection (25). Sync-check protection checks for phase angle difference, magnitude difference, frequency
difference (slip), and optionally, if the three-phase VT frequency is greater than the auxiliary VT frequency.
Two voltage monitor outputs (25VM1 and 25VM2) provide independent dead/live voltage closing logic.
One negative sequence overvoltage element provides protection for phase unbalance or a reverse system
phase sequence (47).
Voltage transformer circuit monitoring adds security by detecting problems in the voltage transformer
sensing circuits and preventing misoperations of the 27P, 47, 59P, and the 51/27 function (60FL).
Directional Power Protection
One directional power element (32) is included in the BE1-951 and can be set for forward or reverse power
protection. The relay can be used for any application requiring directional power flow detection including
intertie protection (interconnects between an electric utility and a source of non-utility generation). The power
measurement algorithm is adapted as appropriate for any possible three-phase or single-phase voltage
transformer connection. Directional Power is calibrated on a three-phase basis regardless of the voltage
transformer connection used.
Frequency Protection
Six over/underfrequency protection function blocks are provided: 81, 181, 281, 381, 481, and 581. Each
function block can be set for overfrequency or underfrequency operation.
Breaker Failure Protection
One breaker failure protection block (BF) provides programmable breaker failure protection.
Fuse Loss Protection
A fuse loss function protects against false tripping due to a loss of voltage sensing.
General Purpose Logic Timers
Two general purpose logic timers (62, 162) with six modes of operation are provided.
Setting Groups
Four setting groups allow adaptive relaying to be implemented to optimize BE1-951 settings for various
operating conditions. Automatic and external logic can be employed to select the active setting group.
Virtual Control Switches
BE1-951 virtual control switches include one virtual breaker control switch and four virtual switches.
Trip and close control of a selected breaker can be controlled by the virtual breaker control switch (101). The
virtual breaker control switch is accessed locally from the front panel human machine interface (HMI) or
remotely from the communication ports.
Additional control is provided by the four virtual switches: 43, 143, 243, and 343. These virtual switches are
accessed locally from the front panel HMI or remotely from the communication ports. Virtual switches can
be used to trip and close additional switches or breakers, or enable and disable certain functions.
Virtual Lockout Protection
The BE1-951 includes two virtual lockout functions (86 and 186) that emulate electric reset lockout relays
and operate as a simple flip/flop. When the trip input is asserted, the output of the function toggles to the true
state and when the reset input is asserted, the output of the function toggles to the false state. If both inputs
are asserted at the same time, the trip input always has priority. The state of the lockout (latch) is stored in
non-volatile memory.
