Utility Relay Company AC-PRO-II, Instruction Manual

Page: 34 / 56

AC-PRO-II
®
Instruction Manual www.utilityrelay.com
Page 32
If residual GF is used, make sure it is temporarily turned off.
To test the ST pick-up, temporarily set ST I
2
T off and apply a
short pulse of current that is 10% or 20% less than the ST
pick-up setting. Continue applying short pulses of current
while increasing the current for each pulse until a ST trip
occurs. The first current where a ST trip occurred is the ST
pick-up.
To test the ST delay, turn ST I
2
T on again (if applicable) and
apply a current that is at least 10% greater than the ST pick-
up current.
The trip time should fall within the time band shown on the
Time-Current-Curves.
**** NOTE ****
To bypass Instantaneous-on-Close (I-CLOS) when
primary injection testing at high currents, power the
AC-PRO-II prior to applying current using USB
power via a laptop or a mini-USB wallpack. See
section 11.12 for I-CLOS description.
If residual GF is used, make sure it is temporarily turned off.
Test the Instantaneous pick-up and trip time in the same
manner as ST in Section 14.3.
If residual GF is used, make sure it is temporarily turned off.
If Ground Return GF is used, NOL cannot be used.
To perform a primary injection test of the NOL function,
temporarily shift the Phase C CT secondary wires to the
neutral CT input terminals on the AC-PRO-II. Connect a
laptop, PC, or USB wallpack to the front mini-USB port of the
display to power the trip unit. Primary injection into Phase C
will simulate neutral current. If this testing method is not
preferred, the NOL function can be tested using the
Secondary Injection Test Set. See Section 15.0.
Test the Neutral Overload Pick-up and trip time in the same
manner as LT in Section 14.2.
Refer to Neutral Overload formula in Section 18.4.
**** NOTE ****
A simple shortcut is to note that the trip time (center
of the curve) at 3 times the NOL pick-up current is 4
times the NOL Delay setting.
For example:
If NOL Pick-Up is 2000A and Delay is 20.0S, then the
trip time at 6000A (3 times 2000A) is 80 sec. (4 times
20 sec).
**** NOTE ****
Only Phase current will power the AC-PRO-II. When doing
primary injection testing of the NOL, the AC-PRO-II must
be powered via 24VDC or the USB port.
When the AC-PRO-II is set for residual GF protection, the
trip unit calculates ground fault current.
With GF Pick-Up and Delay set to the required values,
primary injection testing any one of the three poles will
provide a GF trip.
Test the GF Pick-Up and trip time in the same manner as ST
in Section 14.3.
When the AC-PRO-II is set for ground return GF protection,
the neutral current input is used for direct measurement of
the GF current.
To perform a primary injection test of ground return GF
protection, temporarily shift the Phase C CT secondary wires
to the Neutral CT input terminals on the AC-PRO-II.
Connect
a laptop, PC, or USB wallpack to the front mini-USB port of
the display to power the trip unit. Primary injection into
Phase C will simulate ground return current.
If this testing
method is not preferred, the ground return GF function can
be tested using the Secondary Injection Test Set. See
Section 15.0.
Test the GF pick-up and trip time in the same manner as ST
in Section 14.3.
To test QT-GF the AC-PRO-II QUICK-TRIP switch module
must be connected to the trip unit as shown in Figure 7.1.
With QT-GF pick-up set to the required value and the
QUICK-TRIP selector switch turned to the on position, testing
any one of the three poles will provide a QT-GF trip.
Test the QT-GF pick-up and trip time in the same manner as
the normal GF function.
Proper breaker CT polarity is always recommended, and is
required for residual GF and residual QUICK-TRIP GF
protection. Without proper CT polarity wiring, a nuisance GF
trip will probably occur.
With the breaker in service on a
3-phase system, the last trip data with a reversed
polarity phase CT will show the GF current magnitude
as approximately two times the phase current of the CT
connected in reverse polarity
.
Since primary injection testing normally tests only one phase
at a time, a breaker CT with reversed polarity will not be
detected with the normal tests. By using the following
method, a primary injection test set can be used to test for
proper CT polarity.
14.3 Short Time Trip Test
14.4 Instantaneous Trip Test
14.5 Neutral Overload (NOL) Trip Test
14.6 Ground Fault Trip Tests
14.6.1 Residual Ground Fault Trip Test
14.6.2 Ground Return Fault Trip Test
14.7 QT-GF Trip Test
14.8 CT Phasing Test for GF