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41-348.11C
0.2 amperes 60 hertz and reading the voltage drop
across the reactor with a high impedance true rms
reading voltmeter. The voltage drop will be between
20 and 26 V (true rms). For 0.4 amperes input, the
reading should be between 24 and 31 volts (true
rms).
1. Minimum Trip Current with I
amperes, apply 0.14 ± 5% amperes operating
current to each operating circuit of the relay. The
relay should operate and the indicator lamp
should light.
2. Differential Characteristic
a) Apply I
of 5 amperes and adjust the operat-
R
ing current until the relay operates. The relay
should operate and the indicator lamp should
light with an operating current of 0.25
± 0.012 amperes. Repeat for each phase of
the relay.
b) Apply I
of 60 amperes and adjust the oper-
R
ating current until the relay operates. The
relay should operate and the indicator lamp
should light with an operating current of 30
± 3 amperes. Repeat for each phase of the
relay.
8.2
MAINTENANCE
All relays should be checked once a year to detect
the electronic component failures which occur on a
random basis. The tantalum capacitors C1, C2, C3,
C4 and C13 may have a common mode failure char-
acteristic and should be checked visually for symp-
toms of electrolyte leakage every year and replaced
if necessary.
9.0 CALIBRATION
Use the following procedure for calibrating the relay if
the relay adjustments have been disturbed. This pro-
cedure should not be used until it is apparent the
relay is NOT in proper working order.
4
1. Minimum Trip Current – Connect the relay per
set at zero
R
2. Percentage Slope Characteristic (Low Cur-
3. Electrical Checkpoints – See Table 1 (page
10.0 ELECTRICAL CHECKPOINTS
Connect relay per test circuit of Figure 12 (page 15).
All voltage readings should be made with a high
resistance voltmeter. Refer to Figure 4 (page 9) for
the location of checkpoints. Voltage readings are
approximate. The voltage readings "Input to Ampli-
fier" should NOT be taken with relay in service.
11.0 RENEWAL PARTS
Repair work can be done most satisfactorily at the
factory. However, interchangeable parts can be fur-
nished to customers who are equipped for doing
repair work. When ordering parts, always give the
nameplate data.
SA-1 Generator Differential Relay - Class 1E
test circuit of Figure 12 (page 15). With switch K
open, adjust the operating resistor in the rear of
the relay until the relay operates with I
0.14 amperes. Do not make adjustments to the
resistor unless the dc is disconnected.
The indicator lamp should light when the relay
operates.
Repeat for each phase of the relay.
rent) – Set I
equal to 5 amperes and adjust the
R
restraint resistor in the rear of the relay until the
relay operates with I
0
Do not adjust resistor with dc applied to relay.
The indicator lamp should light when the relay
operates.
Repeat for each phase of the relay.
Percentage Slope Characteristic (High Cur-
rent) – Set I
equal to 60 amperes for the operat-
R
ing current of 30 amperes. Replace the resistor
R17 if necessary. The value of R17 can be
between 0 and 100 ohms. Repeat for the other
two phases, if necessary, replacing R18 and R19
respectively.
page 6)
equal to
0
= 0.25 ± 0.012 amperes.
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