U.2.35
Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Installation
Connection
Figure 2.24
5U Rear Panel, INT5 and INT1/INT6 I/O Interface Board, SEL-421 Relay.
(The INT5 board is the 200-addresses slot; the INT1/INT6 board is the 300-addresses slot.)
Rear-Panel Symbols
There are important safety symbols on the rear of the SEL-421 Relay (see
). Observe proper safety precautions when you connect the relay at
terminals marked by these symbols. In particular, the danger symbol located
on the rear panel corresponds to the following:
Contact with instrument
terminals can cause electrical shock that can result in injury or death
. Be
careful to limit access to these terminals.
Figure 2.25
Rear-Panel Symbols.
Screw Terminal
Connectors
Terminate connections to the SEL-421 Relay screw terminal connectors with
ring-type crimp lugs. Use a #8 ring lug with a maximum width of 0.360 in.
(9.1 mm). The screws in the rear-panel screw terminal connectors are #8-32
binding head, slotted, nickel-plated brass screws. Tightening torque for the
terminal connector screws is 9 in-lb. to 18 in-lb. (1.0 Nm to 2.0 Nm).
You can remove the screw terminal connectors from the rear of the SEL-421
Relay by unscrewing the screws at each end of the connector block. Remove
the connector by pulling the connector block straight out. Note that the
receptacle on the relay circuit board is keyed; you can insert each screw
terminal connector in only one location on the rear panel. To replace the screw
terminal connector, confirm that you have the correct connector, push the
connector firmly onto the circuit board receptacle, and reattach the two screws
at each end of the block.
i3369a
Danger Symbol
DC Input Symbol
Grounding
Terminal
Symbol
Summary of Contents for SEL-421
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