7-4
Maintenance and Testing
Date Code 20000421
SEL-251, -2, -3 Instruction Manual
We recommend testing the SEL-251 Relay with a latching relay to simulate line breaker auxiliary
contact action. This ensures proper assertion and deassertion of the circuit breaker status
function assigned to an input on the back panel.
I
NITIAL
C
HECKOUT
The initial checkout procedure should familiarize you with the relay and ensure that all functions
are operational. Study
Functional Specification and Description
in
Section 2: Specifications
,
Command Descriptions
in
Section 3: Communications
, and
Section 4: Event Reporting
for a
complete understanding of the relay capabilities.
Equipment Required
The following equipment is necessary for initial checkout.
1. Terminal with EIA-232 serial interface
2. Interconnecting cable between terminal and relay
3. Source of control power
4. Source of three-phase voltages and currents
5. Ohmmeter or contact opening/closing sensing device
6. Plug-in mating connectors/wiring harness (Plug-In Connector model only)
Checkout Procedure
In the procedure below, you will use several relay commands.
Section 3: Communications
provides a full explanation of all commands. The following information should allow you to
complete the checkout without referring to the detailed descriptions.
Note:
In this manual, commands to type appear in bold/upper case:
OTTER
. Keys to press
appear in bold/upper case/brackets:
<ENTER>
.
Relay output appears in the following format:
Example 21.6 kV distribution feeder Date: 04/01/93 Time: 01:01:01
♦
♦
Step 1
Purpose:
Be sure you received the relay in satisfactory condition.
Method:
Inspect the instrument for physical damage such as dents or rattles.
♦
♦
Step 2
Purpose:
Verify the requirements for the relay logic inputs, control power voltage level, and
voltage and current inputs.