3
Date Code 20170804
Quick-Start Guide
SEL-300G Relay
Relay Commissioning Procedure
Commissioning Procedure
Step 1. Ensure that dc power is removed from the SEL-300G dc
circuits by opening the appropriate dc breaker or removing dc
fuses.
Step 2. Verify the accuracy and correctness of the ac and dc
connections by performing point-to-point continuity checks on
the circuits associated with the SEL-300G Relay.
Step 3. Make any necessary modifications to the relay output contact
jumper positions, password or breaker command jumper
positions. Refer to
for additional details
and instructions on how to access and modify these jumpers.
Step 4. Using a voltmeter, check the polarity of dc voltage on the
energized side of the dc circuit breaker or fuse block that
isolates the SEL-300G dc power supply inputs, terminals Z25
and Z26. Refer to
. Verify continuity between the
positive, low-side terminal of the breaker or fuse block and
terminal Z25 marked “+.” Verify continuity between the
negative, low-side terminal of the breaker or fuse block and
terminal Z26 marked “-.” This step is important because the
SEL-300G 24/48 Vdc power supply is polarity sensitive.
Figure 2
DC Supply Polarity, Continuity Checks
Step 5. Select models of the SEL-300G_1 or SEL-300G_Y are
equipped with polarity sensitive, high current interrupting
output contacts. When the relay is so equipped, it will have +
polarity marks above even-numbered terminals in the B-series,
such as B02, B04, etc. If your relay output contacts include
CAUTION
Do not apply reverse polarity dc
voltage or ac voltage to terminals
Z25 and Z26 of SEL-300G Relays
rated for 24/48 Vdc applications.
Relay failure and permanent power
supply damage will result from
application of reverse polarity dc
voltage to relays rated for 24/48 Vdc
applications
DWG: M300G103
SEL-300G Relay
(Partial)
ohms
com
0.0 ohms
To Battery
Bank
+ DC
com
+Vdc
DC fuse block
(or DC circuit
breaker) with
fuses removed.
1
2
3
1
2
3
Z26
Z25
Verify correct DC
polarity at fuse
block input.
Verify continuity
from fuse block +dc
to relay +dc power
supply terminal Z25.
Verify continuity
from fuse block –dc
to relay –dc power
supply terminal Z26.
NOTE:
If an output contact is
polarity marked, do not use it to
switch ac control signals. If an output
contact is not polarity marked, it is not
polarity sensitive and can be
connected with either terminal at the
higher potential.
Summary of Contents for SEL-300G
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