OHIO SEMITRONICS PC5 Series Use and care manual

OPERATION & CALIBRATION MANUAL
PC5 SERIES WATT TRANSDUCERS
This manual applies to both PC5 (50 and 60 Hertz) and PC4 (400 Hertz) Watt Transducers.
By David W. MILLER
Edited and revised by William D. Walden September, 1998
OHIO SEMITRONICS, INCORPORATED
Copyright by David W. Miller and Ohio Semitronics, Inc.
September 1998
OHIO SEMITRONICS, INC.
4242 Reynolds Drive
Hilliard, Ohio 43026
Phone: [phone]
Fax: [phone]
E-mail: [e-mail]
http://www.ohiosemitronics.com
PC5-MANUAL
OSI # A-7004-01, Rev.A, 11/28/04

Preface to the PC5 Operation and Calibration Manual
By William D. Walden
Ohio Semitronics, Inc.
The PC5 Transducers
The PC5 series of transducers are true four quadrant multipliers for calculating electric power in watts.
The output signals are bi-directional. If the direction of power flow reverses as it may in a facility that has
co-generation, the sign of the output reverses. All PC5 watt transducers are calibrated at Ohio
Semitronics, Inc. using standards that are traceable to the National Institute of Standards and Technology
(NIST).
The PC5 series watt transducers are unique in that these Hall effect watt transducers do an excellent job
calculating power where severe distortion or chopped current and voltage wave shapes exist.
Watt transducers are available from Ohio Semitronics, Inc. in 1, 2, 2 ½, and 3 element versions and with
output signals of 0 to ±1 mADC, 0 to ±5 volts, 0 to ±10 volts DC, 4 to 20 mADC, or 4 to 12 to 20 mADC,
where 4 mADC represents negative full scale, 12 mADC represents 0, and 20 mADC represents positive
full scale. We are very flexible with this series. If you have special requirements, please contact us.
Mr. David W. Miller
David W. Miller is Vice President of Ohio Semitronics, Inc. He has been with the company since its
founding in 1964. Mr. Miller personally designed most of the transducers that Ohio Semitronics, Inc. is
presently manufacturing.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page ii
CONTENTS
SECTION DESCRIPTION PAGE
1 Operating Principles 1
2 Types 1
3 Rating 1
3.1 Standard PC5 Output 1
3.2 Voltage Inputs 2
3.3 Current Inputs 2
4 Power Factor 4
5 Frequency Range 4
6 Signal Source 4
7 Readout Instruments 5
8, 8.1 Scaling 5
8.2 Ampere turns 6
9 Calibration 6
9.1 General 6
9.2 Adjustments 7
9.3 Final Calibration 8
10 Installation 12
11 Troubleshooting 12
Figure 6 Balance adjust potentiometers 14
Figure 7 Test Connections 15
10/ 2W
Figure 8 Test Connections 15
10/ 3W
30/ 3W
Figure 9 Test Connections 16
30/ 4W
Figure 10 Calibration Test Set-Ups 17
Technical Bulletin 101 Using PTs and CTs with Watt Transducers 18
PT & CT Connection Diagrams Drawing A902-076 Rev. A 12/98
1 and 2 element connections 19
3 and 1 ½ element connections 20
2 ½ element connections 21
PC5 Specification Sheets Last section of this manual.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 1
WATT TRANSDUCER
PC5 SERIES
1. OPERATING PRINCIPLES
The power in an AC circuit is the product of
the voltage, current, and power factor
expressed as P = EI COS where is the
angle by which the current lags (inductive) or
leads (capacitive) the voltage. Power is a
measure of the rate at which work is being
done. Watt (or power) transducers provide a
means of measuring this and provide a signal
proportional to the rate at which work is being
done. The unit of electric power is the watt.
Some convenient power conversions: 1
horsepower=746 watts, 1 watt = 3.41
BTU/hour, 1 watt = 1 DC ampere X 1 DC volt.
The PC5 Watt Transducers utilize Hall Effect
multipliers to provide an output signal propor-
tional to the electric power consumed in a
load. The multipliers provide instantaneous
multiplication of the voltage and the current
on a continuous basis.
2. TYPES
PC5 Watt Transducers come in four types.
A Single Phase (One Element)
This type has one current sensor and
one voltage transformer. This mea-
sures total power in a two-wire circuit.
B Polyphase (Two Element)
This type has two current sensors and
two voltage transformers. This trans-
ducer will measure total power in a 10/
3W or 30/ 3W Delta circuits without
voltage or load restrictions.
C Polyphase (2½ Element)
This type has three current sensors
and two voltage transformers. This
transducer will measure total power in
a 30/ 4W circuit with balanced voltage
and unrestricted load.
D Polyphase (Three Elements)
This type has three current sensors
and three voltage transformers. This
transducer will measure total power in
a 30/ 4W circuit without voltage or load
restrictions.
3. RATING
3.1 STANDARD PC5 OUTPUT
The base unit PC5 Watt Transducer has an
analog signal output of 50 millivolts for single
phase, 100 millivolts for 30/ 3W, 10/ 3W or 30/
4W, 2 1/2 element, or 150 millivolts for 30/
4W. In each case output loading should be
greater than 100K Ω. Figure 1 shows the
output of the base PC5 Watt Transducer.
The sine wave shown is at twice the source
frequency. The "average dc" shown by the
dashed line in the figures below is
proportional to the true power and the sine
wave shown as solid lines is proportional to

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 2
the apparent power.
Figure 1a
Figure 1b
Figure 1c
The Graphs at the left illustrate loads with
the following characteristics:
•Top Figure 1a – Load at unity power
factor.
•Middle Figure 1b – Inductive load at 0.5
power factor.
•Bottom Figure 1c – Pure inductive load or
0 power factor.
In all three cases the dashed line represents
the real average power or the work being
done by the load.
The AC ripple, which represents apparent
power, is eliminated using the simple filter
circuit shown below.
200 OHMS
100 ufd
Input Output
Figure 2
In all cases the base outputs are filtered and
amplified to provide 0 to 1mA, 0 to 5 volts, 0
to 10 volts or 4 to 20mA's by adding the
option letter to the end of the model number
when ordering the transducer. Base models
(models with non-amplified outputs) are no
longer available from Ohio Semitronics, Inc.
except by special request.
2
2
p t( )
A
6.28
0
t
0 1.57 3.14 4.71 6.28
2
1.33
0.67
0
0.67
1.33
2
2
2
p t( )
A
6.28
0
t
0 1.57 3.14 4.71 6.28
2
1.33
0.67
0
0.67
1.33
2
2
2
p t( )
A
6.28
0
t
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2

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 3
OUTPUT OPTION
Suffix Letter
OUTPUT
A 0 to ±1 mADC
Self powered.
B
0 to ± 1 mADC
Requires 120 volts AC instrument
power.
C 0 to ± 10 Volts DC
Self powered.
D
0 to ±10 Volts DC
Requires 120 volts AC instrument
power.
E
4 to 20 mADC
Requires 120 volts AC instrument
power.
E2
4 to 20 mADC
Requires 24 volts DC in the
external loop.
X5
0 to ±5 volts DC
Requires 120 volts AC instrument
power.
CX5 0 to ±5 volts DC
Self powered.
Options A , C, & CX5 the self powered models
should maintain the voltage within:
120 volt models: 85 to 135 volts AC
240 volt models: 200 to 280 volts AC
480 volt models: 380 to 550 volts AC
The standard specification sheets show the
Effective Range of the voltage and current.
These inputs indicate the ranges over which
the transducer will be within its specified
accuracy. The rated output "RO" is the
calibration point at which the 1mA, 5V, 10V or
20mA is obtained. All transducer outputs will
over range by 20% as long as the voltage and
current are in their effective range.
3.2 VOLTAGE INPUTS
PC5 Watt Transducers are designed for
nominal inputs of 120, 240/277 or 480 VAC.
The effective range at the specified accuracy
is 0 to 150, 0 to 300, or 0 to 600 VAC. These
wide ranges do not apply to Options A or C,
which are limited as follows: 85 to 135 V for 0
to 150 V models, 200 to 280 V for 0 to 300 V
models, and 380 to 550 V for 0 to 600
models.
3.3 CURRENT INPUTS
Standard models are rated from 1 through
1000 amperes. Models with input current up
to 20 amperes connect direct to the terminal
strips. Models above 20 amperes use a
current transformer. Current connections are
made through the window of the current
transformer.
(A) Current Transformers
Current transformers step the current
down to 5 amperes. When specified
by model number these current
transformers are calibrated as part of
the watt transducer and should not be
interchanged among different watt
transducers. Extending the leads of
the current transformers is permissible
as long as 12-gauge wire is used and
the VA rating of the transformer is not
exceeded. See Page 18 Technical
Bulletin 101 for wire sizes.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 4
CAUTION
Only qualified personnel should install
the current transformer. Do not apply
line current through the window of the
current transformer with the secondary
leads open. A SEVERE SHOCK TO
THE INSTALLER OR DAMAGE TO
THE CURRENT TRANSFORMER
MAY RESULT.
If necessary to operate the current
transformer without the watt transducer, bolt
the two secondary leads together and mark
with a CAUTION tag.
4. POWER FACTOR
All PC5 watt transducers are corrected for
power factors from 0 lead to unity to 0 lag (0°
to ±90°) and are within the specified accuracy
listed.
5. FREQUENCY RANGE
The PC5 Watt Transducers are designed to
operate from 50 to 70 Hz. However, good
results can be obtained from 40 to 400 Hz.
See specification sheet for PC4 Models when
400 Hz is required.
6. SIGNAL SOURCE
A Options A & B, 0 to 1 mADC constant current output, may be used to drive a 1
milliampere analog meter directly..
Figure 3
Or, may be scaled for a digital meter using a load resistor.
1 2 3 4 5 6 7 8 9 10 11 12 1/2 horsepower
single phase motor
load
115 volts AC
PC5-001B
LRB 500 load
resistor
0276
Watts
115 volts
-+
Figure 4

The value of the load resistor may be
calculated using Ohm’s Law:
R = E/I Where E is the desired
voltage and I is 0.001 (1 mADC).
B Option C & D, 0 to 10 VDC constant
voltage output, supply up to 5 mA
into a 2000 Ωload.
C Option E, 4 to 20 mADC output for
industrial controls, has its own power
source and may be used for loads
from 0 to 1500 Ω.
D Option E2, 4 to 20 mADC
output requires 16 to 40 volts
DC in the external loop.
7. READOUT INSTRUMENT
Analog instruments, which accept a 0 to
1mADC input, may be directly connected to
the output terminals of the watt transducer
with option A or B, to provide a direct
reading in power. Watt Transducers may be
used to supply signals for recorders, analog
to digital converters, computers, digital
panel meters, etc.
8. SCALING
8.1
OSI has a complete line of watt transducers
for various applications. These are
designed for a particular voltage and current
range, and are calibrated as a package. If a
watt transducer is to be used with user
supplied current and potential transformers;
the following information will be helpful.
MODEL PHASE ELEMENTS REQUIRED
PT’s CT’s
CALIBRATED
WATTS AT 1mADC
PC5-001B 10/ 2W 1 1 1 500
PC5-004B 10/ 3W 2 * DIRECT 2 1000
PC5-004B 30/ 3W 2 2 2 1000
PC5-7.5B 30/ 4W 2½ 2 3 1500
PC5-007B 30/ 4W 3 3 3 1500
* Direct Connections for 120 V line to
neutral. Refer to drawings A902-082 and
A902-076, PG. 23 & PG. 23 for PT's & CT's
connections.
The power measured in a circuit in which
current and potential transformers are used
is equal to the power rating of the watt
transducer multiplied by both the current
transformer and potential transformer ratios.
If only current transformers are used, then
multiply by the current transformer ratio.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 6
Consider a PC5-004B rated at 5 amperes,
120 V, 30/, 3W transducer calibrated for
1000 watts at 1 mADC. It is connected to a
480 VOLT, 200 ampere three phase power
system. The potential transformer ratio is
480 to 120 or 4. The current transformer
ratio is 200 to 5 amperes or 40. The full-
scale power will equal 1000 X 4 X 40 or 160
kW. 0 to 1mA is proportional to 0 to 160
kilowatts.
8.2 AMPERE TURNS
Adding turns through the window of the
sensor can change current transformers
primary ratios. Consider a 100-ampere
transformer that you would like to use in a
25-ampere circuit. Wind four turns through
the transformer window. The net result on a
PC5-058B which has a normal full scale of
10 kilowatts and is supplied with a 100:5
current transformer, will be a watt
transducer set up to give a full scale of 1 mA
output at 2.5KW. The maximum current
rating for the transformer or transducer will
be 25 amperes. The picture below is shown
with 4 amp turns. Count only the turns that
pass through the window of the transformer.
H1
Primary
Secondary
Figure 5
9. CALIBRATION
All PC5 Watt Transducers are factory
calibrated and checked 100% for voltage
and current linearity, power factor, and initial
set point. Temperature is checked on
random samples. Instrumentation used for
calibration is traceable to N.I.S.T. (National
Institute of Standards and Technology)
All PC5 Watt Transducers are calibrated on
single-phase with the current coils or current
sensors in series and voltage transformers
in parallel. Polarities are chosen to produce
a positive output on terminal 2 of the watt
transducer. Ideally, the transducer is
energized from a precision instrument
calibrator but adequate results are obtained
by using commercial power and a single-
phase 0.1% Wattmeter standard. The
Wattmeter standard current circuit is
connected in series with the current coils or
sensor of the watt transducer under test.
The voltage transformers are connected in
parallel. Refer to Figure 11 (A) & (B), PG.
21.
9.1 GENERAL
A The Wattmeter standard must be
capable of the desired range of input
voltage and current required
calibrating the particular PC5 Watt
Transducer.
Since all PC5 Watt Transducers will
be calibrated using a single phase
source, the actual wattmeter standard
reading will be half of the total
specified output on 2 elements and
1/3 of the total specified output on 3
elements PC5 Watt Transducers.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 7
First Example: PC5-004B, 30/ 3W has
a specified output of 1mA
proportional to 1KW. Using the
single-phase calibration method, the
Wattmeter standard would be set at
500 watts full scale and the PC5
would be calibrated for a 1mA output
at the 500-watt point on the
wattmeter.
Second Example: PC5-007B, 30/ 4W
has a specified output of 1mA
proportional to 1.5KW. Using the
single-phase calibration method, the
Wattmeter standard would be set at
500 watts and the PC5-007B would
be set to 1 mA at the 500-watt point
on the Wattmeter standard. In each
case, each element of PC5-007B is
measuring the full-scale current &
voltage.
B A digital meter capable of 10-
microvolt resolution for the base watt
transducer with outputs of 50, 100, or
150 millivolts is required and digital
meter capable of 1-millivolt resolution
for all others.
C A precision load resistor of 1K Ω,
0.05% should be used for the 1mA-
output units, option A & B and a
precision resistor of 500 Ω, 0.05%
should be used for option E.
D If the full-scale line current required is
not available; amp-turns through the
current transformer or transducer
window may be used. The windings
must be distributed uniformly around
the current transformer or transducer
and not pulled tightly against the unit.
E If current transformers are not
calibrated with the PC5 the following
additional errors may be expected:
3% 50 and 100 ampere range.
1.5% 200 ampere range.
0.75% 400 & 600 ampere range.
0.3% 1000 ampere range and up.
F Apply power to all voltage potential
circuits for 20 minutes, (this includes
115 VAC instrument power if you
have PC5 with option B, D, or E)
before calibration is attempted.
G Calibration of the watt transducer
should be made at or as close to
unity power as possible.
H Calibration of all standard PC5 Watt
Transducers is scaled for standard
power levels such as 100, 500, 1000,
2000 Watts, etc. Refer to the PC5
specifications for the "Watts at Rated
Output".
9.2 ADJUSTMENTS
Overall calibration and zero adjustments are
located through the lid underneath the
plastic caps. If the lid has a black plastic
cap over the zero opening, do not remove,
this is not an adjustment. Balance
adjustments for 2, 2½, and 3 elements are
located inside the can. Refer to Figure 6 for
location.

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 Ωprecision resistor.
For E option, load the output with a
500 Ωprecision 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

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.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 10
B Example: 10/ 3W, 30/ 3W, 2 Elements)
Model PC5-062D
Voltage 240 VAC
Current 100 A AC
Rated Output 10 V @ 40 kW
External Sensor Required 2 (Factory Supplied 100:5 current transformers)
Test Connections Drawing Figure 8B
Standard Wattmeter Set-Up 240 V, 100 A FS @ 20 kW or 240 V, 10 A FS @ 2 kW
Accuracy ± 0.50% FS
Refer to Figure 10A or 10 B on page 17
Calibration Test Set-Ups, make the
necessary connections between the
calibration and Figure 8B on page 15.
Please note if the AC current source will not
supply the 100 amperes, ampere-turns may
be used. For instance 10 turns through the
window of each current sensor will produce
a 100-ampere current signal when 10
amperes are applied.
Energize the voltage and apply the neces-
sary current to obtain either 20 kW or the
2kW reading if 10 ampere turns are used in
the Standard Wattmeter.
Adjust the "CAL" trimpot, (located on the
PC5-062D) for a 10 V ± 0.50% FS. Like-
wise, hold the current at 100 amperes and
change the voltage such that the power
reading goes from 0 to 20 kW. Next, with
the voltage potential at 240 VAC and current
adjusted for a 20 kW reading, change the
voltage linearity should be within ± 0.50%
FS.
C Example: 30/ 4W, 2½ Element)
Model PC5-7 .5D
Voltage 120 VAC
Current 5 A AC
Rated Output 10 V @ 1500 kW
External Sensor Required None
Test Connections Drawing Figure 9A
Standard Wattmeter Set-Up 120 V, 5 A FS 500 W
Accuracy ± 0.5% FS
Refer to Figure 10A or 10B on page 17
Calibration Test Set-Up, make the required
connections between the calibration and the
direct connections in Figure 9A on page 16.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 11
Energize the voltage and apply 120 VAC,
now energize the current and apply the
necessary current or obtain a reading of 375
watts on the Standard Wattmeter. Adjust
the "CAL" trimpot (located on the PC5-7.5D
lid) for a 10 VDC ±0.001 V reading at
terminals 1 & 2.
With the voltage maintained at 120 VAC,
change the current such that the power
reading goes from 0 to 375 watts or 75% full
scale. The output should not change more
than ±0.005V from the Standard Wattmeter
reading or ±0.5% FS. Likewise, hold the
current at 3.75 amperes and change the
voltage such that the power reading goes
from 0 to 375 watts. Next, with the voltage
potential at 120 V and current adjusted for a
power reading of 375 watts, change the
power factor from unity to zero for both lead
and lag. Both current and voltage linearity
should be within ±0.5% FS.
D Example: (30/ 4W, 3 Element)
Model PC5-007A
Voltage 120 VAC
Current 5 A AC
Rated Output 1 mA @ 1500 Watts
Load On Output Required 10 K Ω± 0.05%
External Sensor Required None
Test Connections Drawing Figure 9B
Standard Wattmeter Set-Up 120 V, 5 A FS @ 500 W
Accuracy ± 0.5% FS
Refer to Figure 10A or 10B Calibration Test
Set-Up on page 17, make the required
connections between the calibration and the
direct connections in Figure 9B on page16.
Energize the voltage and apply 120 VAC,
now energize the current and then apply the
necessary current to obtain the 500-watt
reading on the Standard Wattmeter.
Adjust the "CAL" trimpot (located in the
PC5-007A lid) for a 1 VDC ±0.001 V reading
at terminals 1 & 2.
With the voltage maintained at 120 VAC,
change the current from 0 to 500 watts. The
output should not change more than ±0.005
V from the standard wattmeter reading of
±0.5% FS.
Since the PC5 has option A, the voltage
should be between 85 to 135 VAC because
the amplifier power supply uses the input
voltage. Voltage linearity can not be
checked. Adjust the current back to 500
watts and change the power factor from
unity to zero for both lead and lag. The
output should be within ±0.005 V or ± 0.5%
FS.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 12
10. INSTALLATION
The PC5 may be installed in any position
and in an environment of not more than
+60°C or less than -10°C.
For best accuracy the current carrying cable
should be centered in the window of the
transducer.
Caution must be observed when installing
the current transformers. See section 3.3A.
11. TROUBLESHOOTING
The majority of the problems can usually be
traced to improper connections. The
following list gives some common problems
and solutions.
PROBLEM: No Output
SOLUTION:
1 115 VAC Instrument power not
connected. This applies only
to Options B, X5, D, or E.
2 Voltage not connected.
3 Defective readout.
4 On 30/ 3W or 10/3W units,
could have reverse polarity
either on voltage or current
circuit.
PROBLEM: ½ Output
SOLUTION: All 50-ampere Watt
Transducers require two turns
through the window of the
current transformers.
PROBLEM: 1/3 Output
SOLUTION: 30/ 4W units, polarity of one
phase reversed.
PROBLEM: Doesn't Seem Calibrated
SOLUTION:
1 Calibration point is at the
"Rated Output" not Effective
Watts or Full-Scale range.
2 "CAL" adjustment has been
changed.
3 Customer relies on voltage and
current for power
measurement. This method is
only accurate in a resistive
load.
4 Most industrial loads are either
inductive or capacitive. This
causes a phase shift in the
current relative to the voltage.
For instance with a phase shift
of 30°, the true power would
be 86.6% of E X I. This is
derived by P = E X I X
COS(30°) The cosine of 30°is
0.866, so one can see that
86.6% of E X I is the maximum
power obtainable.
Note that an unloaded
induction motor will run at very
low power factor. What this
means is that very little power
(compared to the rated motor
power) is required to keep the
motor running at constant

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 13
speed. In other words, the
motor is not doing any work.
Power in watts is the measure
of the rate at which work is
being done.
Electric motors often have a
power factor rating. This
rating is for the fully loaded
motor only and will not apply
to an unloaded or partially
loaded motor.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 14
Figure 6a 2 and 2 ½ element models except
those with option E.
Figure 6c All 3 element models.
Figure 6 showing the position of the
balance control on the boards of the PC5
series watt transducers.
From upper left clockwise around
the page. Figure 6a is used for 2 and 2 ½
element models with output options A, B, C, D,
CX5, and X5. Figure 6b is used for 2 and 2 ½
element models with option E. Figure 6c is
used for all 3 element models.
Figure 6b 2 and 2 1/2 element models with
option E, the 4 to 20 ADC output.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 15
12345 6 7 8 9 10 11 12
I E
±
±
+
Output
Instrument
Power
See Note 2
12345 6 7 8 9 10 11 12
IE
±
±
+
Output
Instrument
Power
See Note 2
H1
(a) Using direct connections (b) Using a current transformer
Figure 7
Test Connection for 1 phase, 2 wire, 1 Element Watt Transducer.
I
±
12345 6 7 8 9 10 11 12
Instrument
Power
See Note 2
Output
E
±
12345 6 7 8 9 10 11 12
Instrument
Power
See Note 2
Output
E
±
H1 H1
±
I
(a) Direct connections (b) Using current transformers
BB W W
Figure 8
Test connections for 1 phase, 3 wire & 3 phase, 3 wire, 2 Element Watt Transducers

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 16
±
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Instrument
Power
See Note 2
Output
(a) Direct connections for 2 ½ element PC5
±
EI
+
-
±
I
(b) Direct connections for 3 element PC5
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Instrument
Power
See Note 2
Output
±
E
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Instrument
Power
See Note 2
Output
±
E
H1H1 H1
±
I
(c) Using current transformers with a 3 element PC5
BBB
WWW
Figure 9
a) 3 Phase, 4 Wire 2 ½ element Watt Transducer
Connections.
b) 3 Phase, 4 wire 3 Element Watt Transducer
Connections.
c) 3 Phase, 4 wire 3 Element Watt Transducer
Connections.

PC5 SERIES WATT TRANSDUCER CALIBRATION MANUAL Page 17
LOAD
I
E
±
±
Wattmeter
Standard
Voltage Adjust
Current Adjust
+
-
Output
Precision
Calibrator
±
±
±
±
E
E
I
I
Using a precision Calibrator
such as the Rotek 800A or
811A is the prefered
method of calibration.
Rotek Instruments Corp.
390 Main St.
Waltham, MA 02254
781-899-4611
Figure 10a Figure 10b
Notes:
1) 50-ampere models require two (2) primary turns through the current
transformer window.
2) PC5 models with the suffix B, D, E, or X5 require 120 volts AC instrument
power.
3)
The following indicates a connection between the PC5 watt transducer and
the calibrator.
CalibratorTransducer