Vanguard EZCT-S2A - Manual (Page 87)

REV 1 EZCT S2A USER’S MANUAL
83
5.5 Troubleshooting Guide
PROBLEM DESCRIPTION Probable Cause Suggested Solution
When running the
excitation test, the V
x
voltage is always zero.
The excitation current can
be raised during a test.
• The EZCT S2A X cables are driving a
short circuit. • Check CT shorting screws.
• Check X lead connections.
When running the
excitation test, the V
x
voltage can be raised but
the excitation current is
always zero during a test.
• The EZCT S2A X cable is driving an
opened circuit.
• Check the CT terminal connection.
Cannot reach the CT knee
point voltage (the current
did not reach at least 1A) • The test voltage selected for the test
was too low. You can quickly verify if
the CT was demagnetized by looking
at the last excitation graph.
• Select a higher test voltage for the
test.
When running the
excitation test, the V
x
reading is erratic.
• The EZCT S2A X cable may be opened.
Each X cable has two conductors
going from the clip end to the X
connector on the front panel. If one of
the conductors is opened, the V
x
readings will be erratic.
• Remove X cables from the EZCT
S2A and the CT terminals.
• Check cable integrity using an
Ohm Meter.
The turns ratio reading is
incorrect. • No H cable connection.
• No excitation voltage • Check the H cable connection.
• Check the X cable connection.
Saturation test is correct
but turns ratio test is
erroneous. • V
H
cables problem. • Check the V
H
cable connection.
• Check the V
H
cable integrity with
an Ohmmeter
Turns ratio test of a CT
mounted on a
transformer bushing is
incorrect. • Transformer windings opposite side of
CT windings may not be shorted.
• See Figure 4.