3.3.3.1 Basic Harmonic Restraint Test Procedure
To set up the unit for harmonic restraint testing use the following procedure:
1. Select a current module to provide the desired harmonic. Set the current channel to the
desired harmonic. Use either second, third, or fifth harmonic in conjunction with the
selected frequency.
2. Connect the pair of current output leads from two of the unit’s current channels to the
relay under test so the current from each output is in parallel with one restraint and the
operating coil of the relay. Check to ensure both commons (grounds or earths) share the
same relay terminal.
3. Initiate the outputs. Increase the output to the appropriate harmonic current. It is
recommended that 1.0 ampere of harmonic current be set (it will make the math easier).
If using the HWAVE, set the displayed current to 8.89 amperes RMS (this equals 4
amperes DC half-wave).
4. Increase the fundamental current until the relay operates. To calculate the percent of
harmonic restraint use the appropriate equation below (if using pure harmonic current). If
using the HWAVE refer to the manufacturer’s instruction literature for the appropriate %
Harmonic Curve.
General Electric Type BDD
(
100*
)Harmonic 2()
Current Harmonic 2
%
22
ndlfundamenta
nd
Harmonic
+
=
Westinghouse / ABB Type HU
(
100*
)Harmonic 2()
Current Harmonic 2*2267.1
%
22
ndlfundamenta
nd
Harmonic
+
=
NOTE: Restore the HWAVE channel to a sinewave upon test completion if the HWAVE
feature was used.
34
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