AC-PRO
®
& AC-PRO-II
®
B-292 Secondary Injection Test Set Instruction Manual Rev 1.1
www.utilityrelay.com
Page 13
4.8
Short Time (ST) Test
To test the ST time delay trip:
1)
The first step is to select a test current.
For example, 150% of the ST pick-up.
The desired test current is then 1.5 X
ST
SPU
.
Note, to accurately test the ST delay, the
test current must be at least 110% of the ST
pick-up.
2)
Hold down the Current Preset (13)
while adjusting the Amp Coarse (14)
and Fine (15) pots until the Current (12)
display shows the test current calculated
in step 1.
3)
Set the Phase selector (11) to either
Phase A, B or C.
4)
Push the Clear (8) button to reset the
Timer (6) to zero.
5)
Push the Start (5) button.
6)
When the AC-PRO or AC-PRO-II trips,
the test set current will stop and the
Timer (6) will freeze displaying the trip
time.
7)
Compare the trip time with the TCC
in Figure 9 or Figure 12 for the ST
time band setting in the AC-PRO or
AC-PRO-II.
8)
Verify that the trip unit saved the proper
last trip data.
9)
Repeat for the other two phases if
desired.
4.9
Calculate Instantaneous (I) Pick-Up
Secondary Current
Calculate Instantaneous secondary pick-up
current (I
SPU
) as follows:
For 1-Amp AC-PRO or AC-PRO-II:
I
SPU
= I Pick-Up
CT Primary Rating
Example: If the CT Primary rating is 1600 and
Instantaneous pick-up is 9600 amps, then:
I
SPU
= 9600 = 6.00 amp
1600
For 0.5 Amp AC-PRO or AC-PRO-II:
I
SPU
= I Pick-Up X 0.5
CT Primary Rating
Example: If the CT Primary rating is 1600 and
Instantaneous pick-up is 9600 amps, then:
ST
SPU
= 9600 X 0.5 = 3.00 amp
1600
Note: If CT Secondary Rating is different than 1.0 or 0.5,
use the 0.5 example above and replace 0.5 with the
specific CT Secondary Rating.
Note: If Phase CT and Neutral CT do not have the same
Secondary Rating (i.e. if both not 1-Amp), temporarily
turn off Ground Fault Protection in the Trip Unit when
performing Long Time, Short Time, and Instantaneous
Tests.
