U.2.31
Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Installation
Relay Placement
Relay Placement
Proper placement of the SEL-421 Relay helps make certain that you receive
years of trouble-free power system protection. Use the following guidelines
for proper physical installation of the SEL-421 Relay.
Physical Location
You can mount the SEL-421 Relay in a sheltered indoor environment (a
building or an enclosed cabinet) that does not exceed the temperature and
humidity ratings for the relay. The relay is IEC EN61010-1 rated at
Installation/Overvoltage Category II and Pollution Degree 2. This rating
allows mounting the relay indoors or in an outdoor (extended) enclosure
where the relay is protected against exposure to direct sunlight, precipitation,
and full wind pressure, but neither temperature nor humidity are controlled.
You can place the relay in extreme temperature and humidity locations. The
temperature range over which the relay operates is –40
°
to +185
°
F (–40
°
to
+85
°
C, see
Operating Temperature on page U.1.11 in the User’s Guide
). The
relay operates in a humidity range from 5 percent to 95 percent, no
condensation. For EN61010 certification, the SEL-421 Relay rating is 2000 m
(6560 feet) above mean sea level.
Rack Mounting
When mounting in a rack, use the reversible front flanges to either semiflush-
mount or projection mount the relay. The semiflush mount gives a small panel
protrusion from the relay rack rails of approximately 1.1 in. or 27.9 mm. The
projection mount places the front panel approximately 3.5 in. or 88.9 mm in
front of the relay rack rails. See
for exact mounting
dimensions for both the horizontal and vertical rack-mount relays. Use four
screws of the appropriate size for your rack.
Summary of Contents for SEL-421
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