U.2.39
Date Code 20090715 User’s Guide SEL-421 Relay
Installation
Connection
on page U.1.13, for complete power input specifications.) For the relay
models that accept dc input, the serial number label specifies dc with the
symbol shown in Figure 2.36.
NOTE: The combined voltages
applied to the POWER and MONITOR
terminals must not exceed 600 V
(rms or dc).
The POWER terminals are isolated from chassis ground. Use 16–14 AWG
(1.5 mm
2
–2.1 mm
2
) size wire to connect to the POWER terminals. Connection
to external power must comply with IEC 60947-1 and IEC 60947-3 and must
be identified as the disconnect device for the equipment.
Place an external disconnect device, switch/fuse combination, or circuit
breaker in the POWER leads for the SEL-421; this device must interrupt both the
hot (H/+) and neutral (N/–) power leads. The current rating for the power
disconnect circuit breaker or fuse must be 20 A maximum. Be sure to locate
this device within 9.8 feet (3.0 m) of the relay.
Operational power is internally fused by power supply fuse F1. Table 2.11
lists the SEL-421 power supply fuse requirements. Be sure to use fuses that
comply with IEC 127-2.
You can order the SEL-421 with one of three operational power input ranges
listed in Table 2.11. Each of the three supply voltage ranges represents a
power supply ordering option.
As noted in Table 2.11, model numbers for the relay with these power supplies
begin 04210n (or 04211n), where n is 2, 4, or 6, to indicate low, middle, and
high voltage input power supplies, respectively.
Note that each power supply range covers two widely used nominal input
voltages. The SEL-421 power supply operates from 30 Hz to 120 Hz when ac
power is used for the POWER input.
The SEL-421 accepts dc power input for all three power supply models. The
48/125 Vdc supply also accepts 120 Vac; the 125/250 Vdc supply also accepts
120/240 Vac. When connecting a dc power source, you must connect the
source with the proper polarity, as indicated by the + (terminal #Z29) and –
(terminal #Z30) symbols on the power terminals. When connecting to an ac
power source, the + terminal #Z29 is hot (H), and the – terminal #Z30 is neutral
(N).
Each model of the SEL-421 internal power supply exhibits low power
consumption and a wide input voltage tolerance. For more information on the
power supplies, see Power Supply on page U.1.13.
Table 2.11 Fuse Requirements for the SEL-421 Power Supply
Nominal
Power
Supply
Voltage
Rating
Power Supply
Voltage Range
Fuse F1 Fuse Description
Model
Number
24/48 V 18–60 Vdc T6.3A
H250V
5x20 mm, time-lag, 6.3 A,
high break capacity, 250 V
042102
or
042112
48/125 V 38–140 Vdc or
85–140 Vac
(30–120 Hz)
T3.15A
H250V
5x20 mm, time-lag, 3.15 A,
high break capacity, 250 V
042104
or
042114
125/250 V 85–300 Vdc or
85–264 Vac
(30–120 Hz)
T3.15A
H250V
5x20 mm, time-lag, 3.15 A,
high break capacity, 250 V
042106
or
042116
Courtesy of NationalSwitchgear.com
To Next Page
Loading...
