Sel 421 - Figure 4.2 Power Connection Area of the Rear Panel; Table 4.1 Power Supply Voltage Inputs

U.4.3
Date Code 20090715 User’s Guide SEL-421 Relay
Basic Relay Operations
Connecting and Applying Power
label indicates, the voltage source should be capable of providing at least
35 W. See Power Supply on page U.1.13 for more information on power
supply specifications.
Logic Input Ratings
The serial number label in Figure 4.1 only lists control input voltages for I/O
Interface Boards that have 24 optoisolated inputs, which is determined at
ordering time. In the sample shown, only Slot B contains an INT4 I/O
Interface board, so only one input rating appears. The other types of control
inputs (Direct Coupled) have settable pickup voltages, and do not appear on
the serial number label. See Control Input Assignment on page U.4.65 for
more information.
Connecting and Applying Power
Connect external power to the SEL-421 to perform the initial checkout and
familiarization procedures in this section. For complete information on power
connections, see Power Connections on page U.2.38.
Figure 4.2 shows the portion of the relay rear panel where you connect the
power input.
Figure 4.2 Power Connection Area of the Rear Panel
You can order the SEL-421 with one of three power supplies with nominal
operating voltages: 24/48 Vdc, 48/125 Vdc, and 125/250 Vdc. The two higher
voltage supplies, 48/125 Vdc and 125/250 Vdc, use ac input and dc input. The
relay serial number label on the back of the relay lists voltage ranges that
encompass the nominal voltages.
Table 4.1 shows the nominal voltage inputs and power supply voltage ranges
for dc input, and ac inputs if applicable.
Table 4.1 Power Supply Voltage Inputs
Nominal DC
Voltage Input
DC Input Range
AC Input Range
(30—120 Hz)
24/48 Vdc 18–60 Vdc <35 W N/A
48/125 Vdc 38–140 Vdc <35 W 120 Vac <120 VA
125/250 Vdc 85–300 Vdc <35 W 120/230 Vac <120 VA
Terminal Z29 Terminal Z30 Terminal Z31
Serial
Number
Label
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