BE1-32R, -32 O/U GENERAL INFORMATION
1-1
Figure 1-1. Single-Phase Motoring Protection
SECTION 1 • GENERAL INFORMATION
PURPOSE
BE1-32R, Directional Overpower and BE1-32 O/U, Directional Over/Underpower Relays sense real power (IE
times cos
). These relays are solid state devices that are designed for use in single-phase or three-phase
systems to provide equipment protection for overpower and/or underpower, or for use in the supervisory control
of circuits.
APPLICATION
Directional Power Relays are typically used in applications where excessive power flow in the tripping direction
is bad. Some examples in which over and/or underpower protection is desirable are as follows.
Example:
1.
Where power flows into a generator, indicating loss of prime mover torque (motoring).
2.
Where power flows into the secondary of a station distribution transformer, indicating an industrial or
private customer is supplying power into the utility system.
3.
Where excessive load has been connected to a system.
4.
Where overload has been placed on a distribution system.
5.
Where overspeeding is a prime concern.
6.
Where an open breaker creates an overload on a local generation facility.
7.
Where loss of excitation can be determined by var sensing.
Example 1, Anti-Motoring
When a synchronous generator, operating in parallel with
a power system, loses prime mover torque, it remains in
synchronism with the system and continues to run as a
synchronous motor. Motoring draws power from the
system to drive the prime mover and can cause severe
damage to the prime mover. Steam turbines require a
constant flow of steam to remove the heat caused by
turbulence or cavitation on or about the blades. Without
this flow of steam, heat builds up and may cause
softening or distortion of the turbine blades. Diesel
engines and gas turbines are less susceptible to
immediate damage, but unburned fuel may present a fire
or explosion hazard.
BE1-32 Directional Power Relays can detect power flow
into the generator and disconnect the generator before
the prime mover sustains inevitable damage. Unlike the
conditions arising from faults, the electrical conditions
involved in anti-motoring protection are balanced.
Therefore, single-phase relay protection is adequate.
Figure 1-1 shows connections for single-phase relay
(type B or V sensing). This connection measures real
power if the system voltages are balanced.
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