Date Code 20080110 Testing and Troubleshooting 10-31
SEL-387E Instruction Manual
Step 4.
Purpose: Apply fundamental current to pick up the 87R element.
Method: Turn on the first current test source connected to the Winding 1 input (IAW1)
equal to the TAP1 setting multiplied by the connection constant A shown in
Table 10.3. The 87R LED will illuminate once current is applied to the relay.
The following test applies to a single-harmonic injection at a time, i.e., only
the second or the fourth harmonic, not both. Set E87W1 = E87W2 = Y1, and
HRSTR = Y. Set the second current source for second-harmonic current (120
Hz for NFREQ = 60 and 100 Hz for NFREQ = 50). Turn on the second
current test source connected to the Winding 1 input (IAW1). Starting at zero
current, slowly increase the magnitude of applied current until the 87R
element deasserts, causing the 87R LED to extinguish completely. Note the
value of the applied current from the second test source. The general
equation to calculate the percentage of harmonic content for a single slope is:
(±5% ±0.10 A (5 A relay) or ±5% ±0.02 A (1 A relay)):
()
[]
100
2PCT
• SLPf•1IRT1IOP = 2F1I
− and
100•
1IOP
2F1I
harmonic%
= (percent)
For inrush conditions, current normally is applied to one side of the transformer,
and the equation simplifies to the following:
⎟
⎠
⎞
⎜
⎝
⎛
−=
200
1SLP
12PCTharmonic%
where
PCT2 = second-harmonic setting in percent
SLP1 = slope 1 setting
For example
SLP1 = 50 percent
PCT2 = 20 percent
⎟
⎠
⎞
⎜
⎝
⎛
−=
200
50
120harmonic% = 15 percent
For values on the second slope, use the following equation:
()
⎟
⎠
⎞
⎜
⎝
⎛
−−−
⎟
⎠
⎞
⎜
⎝
⎛
= 2SLP1SLP
IRT
1IRS
2SLP200•
200
2PCT
harmonic%
where:
PCT2 = second-harmonic setting in percent
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