PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL
Page 9
instrument is not available, the set up shown
in Figure 10A on page 17 will do if the
Standard Wattmeter is used.
Two variacs are used in Figure 10A to give
independent adjustment between the volt-
age and current circuits. The voltage input,
which is represented with the letter "E",
requires a low current 1 ampere variac with
a voltage range of 0 to 150, 0 to 300 or 0 to
600 VAC depending on the PC5 input
voltage under test. The variac for the
current sensors must be capable of the
current required by the PC5 under test and
the load should be resistive, such as cone
heaters.
The following are examples of calibration of
4 types of PC5 Watt Transducers. They are
10/ 2W (1 element) and 30/ 3W (2 elements),
30/ 4W (2½ elements) and 30/ 4W (3
elements).
A particular model number will be picked
from each of the 4 types to show the
standard procedure for calibration. Only the
voltage, current and rated output change
from model to model for that type of unit.
Balance and zeroing adjustments must have
been made previous to the final calibration.
See 9.2A and 9.2B on page 8.
(A)
Example: 10/ 2W, 1 Element
Model
PC5-010B
Voltage
120 VAC
Current
10 A AC
Rated Output
1 mA @ 1 kW
Load on Output Required
1 K
Ω
± 0.05% Resistor
External Sensor Required
None
Test Connections Drawing
Figure 7A
Standard Wattmeter Set-Up
120 V - 10 A FS 1000 W
Accuracy
± 0.5% FS
Refer to Figure 10A or 10B Calibration Test
Set-Ups on page 17, make the required
connections between the calibrator and the
direct connections in Figure 7A on page15.
Energize the voltage and apply 120 VAC,
not energize the current and apply the
necessary current to obtain a 1000-watt
reading on the Standard Wattmeter. Adjust
the "CAL" trimpot (located in the PC5-010B
lid) for a 1 V ± 0.001V reading at terminals
1 and 2.
With the voltage maintained at 120 VAC,
change the current such that the power
reading goes from 0 to 1000 watts on the
Standard Wattmeter. The output should
not vary more than ±0.005V from the
Standard
Wattmeter reading. Likewise, hold the
current potential at 10 amperes and change
the voltage such that the power reading
goes from 0 to 1000 watts on the Standard
Wattmeter from 0 to 1000 watts.
Next, with the voltage at 120 VAC and the
current adjusted for a 1000 W reading,
change the power factor from unity to 0 for
both lead and lag. Current, voltage, and
linearity should be within ± 0.5% FS.
