Cooper Power Systems Kyle Type ME Series, Maintenance Instructions Manual, Page: 17 / 50

S280-75-2
17
INPUT CIRCUITS
WARNING: High voltage. Contact with high volt-
age will cause serious personal injury or death.
Follow all locally approved safety procedures when
working around high voltage lines and equipment.
!
CAUTION: When measuring voltage between
the violet and gray leads be careful not to short
between the gray wire and the B+ terminal. If the gray
wire is shorted to the B+ terminal the Phase Trip #1
board will be permanently damaged.
!
Figure 22.
Measured voltage across minimum-trip resistors.
TABLE 2
Terminal Strip T1 Test Points for Matching Transformers
(100% Minimum-Trip) (Figures 23 and 24)
82040KMA
Figure 23.
Block diagram of matching transformers (Table 2). See Figure 8
for complete block diagram.
To check input signals to the control, measure the voltage
across the minimum-trip resistors and matching transformer
secondaries as follows:
1. Measure voltage across minimum-trip resistors (Figure 22)
with 100% of minimum-trip current applied to control. The
voltage should be approximately:
•
Phase Resistors—0.17-Vac (170 millivolts)
•
Ground Resistors—0.26-Vac (260 millivolts)
NOTE: The above voltages are proportional to the recloser line current
and can be used to calculate the actual load current on the different
phases, using a digital AC voltmeter such as a Fluke 77 series. The fol-
lowing formula can be used.
(Volts on (Resistor
Line Amps = resistor x value amp)
0.17
Example: 0.023-volts (23-millivolts) measured across a 560-amp phase
resistor is equivalent to 75.7-amps recloser-load current.Total accuracy
is approxi5%.
2. Measure voltage across matching transformer secondaries
(Figures 23 and 24) with 100% of minimum-trip current ap-
plied to control. The test terminals on “T1 “ are shown in
Table
2. The voltages should be:
•
Phase Transformers—6.5-Vac
•
Ground Transformers—1.2-Vac
Failure to get these voltage readings can be a result of:
A. Opens in current source, control cable, matching trans-
former windings, or wiring to the transformers and asso-
ciated components.
B. Shorts in the control’s male input-cable receptacle.
NOTE: Matching transformers are interchangeable between Form
2, 3, and 3A controls.
Transformer Terminal Position Voltage Reading (Vac)
GND BRO—RED 1.2
A
φ
ORG—YEL 6.5
B
φ
GRN—BLU 6.5
C
φ
VI—GRY 6.5