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∗ The digital ammeter should be set to display to only three decimal places.
Values beyond three decimal place accuracy are insignificant to the
calibration and should be ignored.
Table 3-2 values are based on ideal phase relations; track volts lead local volts
by 90° and track amperes lead local volts by 24°.
Table 3-4 lists the contact assignments for the relay.
3.2.3. In-Service and Field Calibration Test Procedure
The following procedure should be used anytime a relay is tested in the field. For
example: when a relay has been in operation for any period of time or during initial in-
service testing prior to going into service, or when the environment of temperature,
voltage and frequency is not controlled, as it is in a shop or factory environment.
Connect the circuit shown in Figure 3-1.
1. Set switch S1 to its OFF position.
2. Connect the circuit to a 115VAC, 60 Hz, isolated line.
3. Set Variac T1 to its minimum output setting.
4. Set switch S1 to its ON position.
5. Adjust Variac T2 to obtain 115 VAC ±1% across Variac T1 as read by voltmeter
V2. This voltage must be maintained throughout this test.
6. Slowly adjust Variac T1 to increase its output until all front contacts of the relay
being calibrated just close. Record the value indicated on ammeter A; this is the
pick-up current value and should be within the pick-up current range specified in
Table 3-3.
7. Again slowly increase the output of Variac T1 until the vane in the relay just
touches the top roller. Record the value indicated on the ammeter; this is the full
stroke current value and should be within the full-stroke current range specified
in Table 3-3.
8. Slowly adjust Variac (T1) to decrease the output until all front contacts of the
relay open. Record the ammeter A reading; this is the drop-away (DA) current
value. It should be equal to or greater than 80% of the actual pickup current
value measured in Step 6.
Copyright 2019
Pick-up (PU) Current Value
Full Stroke (FS) Current Value __________________
SM 4574F, Rev. 4, March 2019
PV-250 Track Relay
__________________
3-5
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