8.4
SEL-551 Relay Instruction Manual Date Code 20110408
Testing and Troubleshooting
Acceptance Testing
Acceptance Testing
When: Qualifying a relay model to be used on the utility system.
Goal:
➤ Ensure relay meets published critical performance
specifications such as operating speed and element accuracy.
➤ Ensure that the relay meets the requirements of the intended
application.
➤ Gain familiarity with relay settings and capabilities.
What to test: All protection elements and logic functions critical to the
intended application.
SEL performs detailed acceptance testing on all new relay models and
versions. We are certain the relays we ship meet their published specifications.
It is important for you to perform acceptance testing on a relay if you are
unfamiliar with its operating theory, protection scheme logic, or settings. This
helps ensure the accuracy and correctness of the relay settings when you issue
them.
Equipment Required
The following equipment is necessary to perform all of the acceptance tests:
1. A terminal or computer with terminal emulation with EIA-232
serial interface
2. Interconnecting data cable between terminal and relay
3. Source of relay control power
4. Source of one current at nominal frequency
5. Ohmmeter or contact opening/closing sensing device
Initial Checkout
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 requirements for relay logic inputs, control power
voltage level, and voltage and current inputs.
Method:
a. Refer to the information sticker on the rear panel of the
relay. Actual information stickers vary, but Figure 8.2
provides an example.
b. Check the information on this sticker before applying
power to the relay or starting tests.
c. Be sure your dc supply is correctly adjusted for the
control and logic input requirements. The logic input
voltage rating is jumper selectable. The sticker gives the
factory default voltage rating.
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