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20 Amp Current Sensor AC/DC
1119_0_Product_Manual created: 03/31/08

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20 Amp Current Sensor AC/DC
Designed to be used with:
1018 PhidgetInterfaceKit 8/8/8

1202/1203 PhidgetTextLCD with InterfaceKit 8/8/8

Product Features
Measures AC current up to 20Amps and DC Current from -20Amps to +20Amps.

Dual outputs allow the user to measure both the AC and DC components of complex
current waveforms separately.
The sensor is Ratiometric.

1119 1119_0_Product_Manual created: 03/31/08

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Getting Started
Installing the Hardware
Connecting all the pieces
To measure DC current connect the 20 Amp Current Sensor AC/DC to an Analog Input on
1. the PhidgetInterfaceKit 8/8/8 board using the sensor cable.
To measure AC current use the AC connector.
2.
Connect your power source to the terminal block.
3.
The Kit contains:
A 20 Amp Current Sensor AC/DC

A Sensor Cable

1
2
3
You will also need:
A PhidgetInterfaceKit 8/8/8 or a
PhidgetTextLCD
A USB Cable
1119_0_Product_Manual created: 03/31/08

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Double Click on Phidget InterfaceKit 8/8/8 in the Phidget Control Panel to bring up
1. InterfaceKit-full and check that the box labelled Attached contains the word True.
Make sure that the Ratiometric box is Ticked.
2.
The Amp value of your power source is displayed in the Analog In box. If you do not connect
3. any power source to the sensor board, the Analog In value should be 500 if you use the
DC connector and 0 if you use the AC connector.
You can adjust the input sensitivity by moving the slider pointer.
4.
Double Click on the
icon to activate
the Phidget Control Panel and make sure
that the Phidget InterfaceKit 8/8/8 is
properly attached to your PC.
Testing the 20 Amp Current Sensor AC/DC connected to an
InterfaceKit 8/8/8
Using Windows 2000/XP/Vista
1
2
3
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Testing the 20 Amp Current Sensor AC/DC connected to an
InterfaceKit 8/8/8
Using Mac OS X
Double Click on Phidget InterfaceKit 8/8/8
1. in the Phidget Preference Pane to bring
up the Phidget Interface Kit Example and
check that the Phidget InterfaceKit 8/8/8
is attached.
Make sure that the Ratiometric box is
2. Ticked.
The Amp value of your power source is
3. displayed in the Sensors box. If you do not
connect any power source to the sensor
board, the value should be 500 if you use
the DC connector and 0 if you use the AC
connector.
You can adjust the input sensitivity by
4. moving the slider pointer.
Click on System Preferences >> Phidgets
(under Other) to activate the Preference
Pane. Make sure that the Phidget InterfaceKit
8/8/8 is properly attached.
1
3
4
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Technical Information
This Current Sensor measures AC current up to 20 Amps and DC current between 20 and
+20 Amps. The AC output will give the RMS (Root Mean Square) value of an alternating
current assuming the current is sinusoidal, and the sine wave is varying equally across the
zero point. The AC out can be used for signals that are not varying evenly around the zero
point but the value will output will be the RMS plus a DC component. If a DC signal is being
measured, the AC output will produce a signal that can be used to calculate the current but
without the value representing direction of current flow.
Measuring Current
The Phidgets Current Sensor should be wired in series with the circuit under test, as shown in
the following diagrams.
In the diagrams above and to the right,
the voltage source is represented
by the battery symbol. The load
is represented by a light bulb or
schematic resistor symbol. The current
flowing from the battery to the load is
measured through the current sensor.
PHIDGE
T
S
P
L
U
S
PH
ID
GE
TS
1
00
W
PHIDGE
T
S SENSOR
Current
Sensor 1119_0_Product_Manual created: 03/31/08

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Formulas
The formula to translate SensorValue into Current is:
DC Current (DC Amps) = [(SensorValue/1000) x 50] - 25
AC Current (RMS amps) = (SensorValue/1000) x 27.75
To translate RawSensorValue into Current:
DC Current = [(RawSensorValue/4095) x 50] - 25
AC Current = (RawSensorValue/4095) x 27.75
If you are using a generic Analog to Digital Converter (not a Phidget device):
DC Current = {[Measured Value / (Max
ADC Range - 1)] x 50} - 25
AC Current = [Measured Value / (Max ADC Range - 1)] x 27.75
Analog Input Cable Connectors
Each Analog Input uses a 3-pin, 0.100 inch pitch locking
connector. Pictured here is a plug with the connections
labeled. The connectors are commonly available - refer to
the Table below for manufacturer part numbers.
Cable Connectors
Manufacturer
Part Number
Description
Molex
50-57-9403
3 Position Cable Connector
Molex
16-02-0102
Wire Crimp Insert for Cable Connector
Molex
70543-0002
3 Position Vertical PCB Connector
Molex
70553-0002
3 Position Right-Angle PCB Connector (Gold)
Molex
70553-0037
3 Position Right-Angle PCB Connector (Tin)
Molex
15-91-2035
3 Position Right-Angle PCB Connector - Surface Mount
Note: Most of the above components can be bought at
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Device Specifications
Current Consumption
10mA
Output Impedance
1K ohms
Maximum Measureable AC Current
20A
Maximum Measureable DC Current
±20A
Maximum Measureable AC Frequency
10kHz
Current Conductor Resistance
1.5m
Isolation - Current Loop to Sensor Output 1600V RMS
Maximum Supply Voltage
5.5VDC
Minimum Supply Voltage
4.5VDC
Active Current Consumption
10mA
Terminal Block Recommended Wire Size
10 - 26 AWG
Wire Stripping Length
6-7mm
Offset (no current flowing)
±150mA Max @ 25°C
Total Error
1
±6% Max between -40°C to +85°C
Total Error (Typical)
±1.5% @ 25°C
1
Note about accuracy
We specify maximum error on our sensors using the numbers from the sensor manufacturer.
The maximum error is obtained from testing millions of sensors in a wide temperature range.
The typical error on a given sensor is 25% or less of the maximum error. If you limit your
temperature range at room temperature, the error rate may decrease by another 75%. In
these conditions, a 6% maximum error translates to 1- 2% typical error. For most prototype
applications, our sensors are extremely accurate. If, on the other hand, your application
demands known accuracy, you will need to calibrate every individual sensor.
Mechanical Drawing
1:1 scale 1119_0_Product_Manual created: 03/31/08

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Product History
Date
Product Revision
Comment
August 2005
n/a
Product Release