Sel 751A, Инструкция по эксплуатации

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2.34
SEL-751A Relay Instruction Manual Date Code 20100129
Installation
Arc-Flash Protection: System Installation
jacketed-fiber sections (the jacketed section is counted twice because of its
dual-fiber construction). Transition between the two sections is accomplished
by using a connector splice as shown in
Figure 2.36 .
Figure 2.36 Bare-Fiber Sensor Showing Transition From Bare- to Jacketed-Fiber Section
The bare-fiber loop should be returned through the same general area as the
forward path, providing dual opportunity to sense the same arc-flash event.
This approach ensures that the maximum distance between the relay and the
light-producing event remains below 35 m, irrespective of the SEL-751A dual
V-pin connector orientation.
Care should be exercised not to scratch or otherwise damage the bare sensing
fiber during installation. Surface scratches may result with increased light
leakage and will be detected by the SEL-751A sensor diagnostics. Once
damaged, the fiber must be replaced.
Application Example
Figure 2.37 shows a typical switchgear application example with one
incoming and two radial (outgoing) feeders. All three feeders are protected
with an SEL-751A relay controlling breakers 1, 2, and 3. Radial feeder
breakers 2 and 3 must be tripped for downstream faults, normally located in
the outgoing cable termination compartment. To obtain better coverage,
multiple sensors can be installed in the same compartment, as shown in the
lower right corner of the figure with sensors marked LS1 and LS2.
Bus compartment and the outgoing breaker compartments for breakers 2 and 3
are protected by the incoming feeder breaker 1, with sensors LS1, LS2, and
LS3 connecter directly to the incoming feeder relay (upper right hand corner
of
Figure 2.37 ). Sensor LS1 is implemented as a bare-fiber loop enclosing
entire length of the bus.
When desired radial feeder relays sensors (such as LS3 connected to the lower
right hand relay) can be used to transfer trip the upstream breaker. Logic
equations required for this function are shown in
Output Logic Programming
in Section 4: Protection and Logic Functions .
ST Connection (3/8” diameter hole) V-Pin Connection (5/16” diameter hole)
5/16” diameter hole
3/8” diameter hole