8.5
Date Code 20110408 Instruction Manual SEL-551 Relay
Testing and Troubleshooting
Acceptance Testing
Figure 8.2 Relay Part Number and Hardware Identification Sticker
Power Supply
Step 1. Purpose:
Establish control power connections.
Method:
Connect a frame ground to terminal marked GND on the rear
panel and connect rated control power to terminals marked +
and –. Relays supplied with 125 or 250 V power supplies can be
powered from a 115 Vac wall receptacle for testing. Other
power supplies require dc voltage and are polarity sensitive.
Serial Communication
Step 1. Purpose:
Verify the communications interface setup.
Method:
Connect a computer terminal to the serial port of the relay.
Communication Parameters: 2400 Baud, 8 Data Bits, 1
Stop Bit, N Parity
Cables: SEL C234A for 9-pin male computer
connections, SEL C227A for 25-pin male computer
connections
Step 2. Purpose:
Apply control voltage to the relay, and start Access Level 0
communications.
Method:
a. Apply control voltage to the relay. The enable target
(EN) LED should illuminate. If not, be sure that power is
present.
b. Press the <Enter> key from your terminal to get the
Access Level 0 response from the relay.
The
= prompt should appear, indicating that you have
established communications at Access Level 0
(presuming correct terminal configuration).
The ALARM relay should hold its b-type output contact
open.
If these do not occur, refer to Relay Troubleshooting on
page 8.17.
NOTE: If you are using a battery
simulator, be sure the simulator
voltage level is stabilized before
turning the relay on.
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