13.20
SEL-311C Relay Instruction Manual Date Code 20060320
Testing and Troubleshooting
Test Procedures
Test Procedures
This section includes outline test procedures for overcurrent, directional,
phase distance, and ground distance elements included in the SEL-311C. The
procedures are general, so that they may be applied to any specific element or
zone.
Overcurrent Elements
The SEL-311C includes phase, residual, negative-sequence, and positive-
sequence overcurrent elements. The type of overcurrent element under test
determines the test connections required. Some elements are supervised by
directional elements or distance elements.
The steps necessary to perform an overcurrent element test are shown below.
Step 1. Select element under test.
a. Briefly review the specifications for the element under
test.
b. If the element under test is supervised by other
conditions, be sure that you understand the inputs
necessary to satisfy the supervisory conditions, and the
overcurrent condition.
Step 2. Verify the element setting by executing the SHOWSET
command via a terminal connected to a relay serial port, or by
examining the relay settings via the front-panel LCD display
through use of the Access Level 2 SET command.
Step 3. Select the method used to indicate assertion of the element
under test. Typically, this is accomplished by monitoring an
output contact programmed to indicate only the condition
under test.
Step 4. Make test source connections.
If an unsupervised, single-phase overcurrent element, such as
the 50P1 element, is being tested, a single current source is all
that is required to perform the test.
If a directionally supervised negative-sequence overcurrent
element is to be tested, voltage sources are also required to
satisfy the directional supervision conditions.
a. Make test source connections based upon the
requirements of the test and the availability of sources.
Figure 13.2–Figure 13.6 illustrate the various source
connections you can use.
Step 5. Determine the signals required to operate the element.
a. For unsupervised elements, simply use the following
equations.
b. Fulfilling the requirements of the supervisory
conditions may be more complicated. Refer to the test
procedures appropriate to the supervising element for
details.
Step 6. Apply the test signals.
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