PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL
Page 8
A
Zero Offset:
Energize only the voltage coils of the
watt transducer. Adjust the output at
terminal 1 & 2 within ±1 millivolts.
This applies for PC5's with option A,
B, C, and D. Option A and B must be
loaded with a 1K
Ω
precision resistor.
For E option, load the output with a
500
Ω
precision resistor and adjust
the "Zero" adjustment for 4mA or
2VDC ±2 millivolts.
B
Balance
This adjustment sets the internal
calibration to provide a balanced
output among elements. Balance of
PC5 Watt Transducers is not required
on 1-element units, and is usually not
necessary on 2, 2½, or 3 element
units unless a part is replaced or the
trimpot has been changed. Refer to
page 8, Section 9.3 if balancing is not
required.
If
adjustments
are
necessary, refer to Figure 6 for
internal circuit board locations of the
balanced trimpots. (See Figure 6 on
page 14.)
2 & 2½ Element Watt Transducers
After the test connections are made as
shown in Figures 8A and 8B or Figure 9A,
reverse the polarity of the voltage on
terminals 5 and 6 by switching the leads..
(See pages 15 & 16 for figures 7, 8 & 9.)
Energize the voltage and current and adjust
the power source for a full scale Standard
Wattmeter reading. Now, adjust the internal
balance trimpot for a zero output reading at
terminals 1 and 2.
3 Element 30/ 4W
After the test connections are made as
shown in Figure 9B or 9C, disconnect the
lead from terminal 12 and connect it to
terminal 11, shorting them together.
Reverse leads going to terminals 9 & 10.
Energize the AC power source and adjust
the Standard Wattmeter for a full-scale
output. Adjust L2 balance trimpot for a zero
output at terminals 1 and 2.
Turn off the power source and change the
connections. Remove terminals 9 and short
to terminal 10. Reverse terminals 11 and
12.
Energize the AC power source and adjust
the Standard Wattmeter for a full-scale
output. Adjust L3 balance trimpot for a zero
output at terminals 1 and 2.
9.3 FINAL CALIBRATION
Before attempting the final calibration, read
the section on calibration. Figure 7, 8 and 9
provide all the various standard test
connection diagrams for the PC5 Watt
Transducers. As you can see, the voltage
circuits are in watts, parallel and the current
circuits are in series.
All standard watt transducers are calibrated
at even power levels, such as 100, 500,
1000, etc. Refer to "Rated Output" on the
specification sheet for the calibration point.
The best method of calibration is to use a
Precision Wattmeter Calibrator, if this
