Weidmüller ACT20P User manual

Weidmüller Pty Ltd
ACT20P Bridge
Note: Subject to technical alterations without notice
QS610001101 • 08/2009
Q UICKSTART GUIDE
Operation
General
The ACT20P Bridge is a DIN rail mounted, signal conditioner for
industrial strain gauge bridges. It provides a precise excitation voltage
for the bridge, and converts the input measurement to an isolated
current/voltage signal.
Strain gauge bridges are used for various measurements like weight,
force, tension, pressure, torque, and deflection.
Bridge excitation supply
Voltage sense connections are provided so that the excitation voltage
can be measured at the bridge. Known as ‘remote sensing’ this
method compensates for cabling and contact resistance errors. It is
recommended for all new installations or where an upgrade is possible.
Remote sensing wiring requires three twisted pairs.
TARE adjustment
The installed strain gauge is normally subjected to an initial load
independent of the measurement taken. The TARE connection allows
you to correct for this initial loading by operating a switch.
Alternatively there is a button on the front of the unit (under the front
cover) that performs the same function. Press for two seconds to
correct for the initial load (the ‘CAL HI’ LED will light for one second).
Gauge factor
Every strain gauge has a ‘gauge factor’ which gives the output voltage
at full-scale for a one volt excitation voltage (given in mV/V). You
multiply this by the bridge excitation voltage to get the output voltage
when the gauge is fully loaded. For example, a load cell with 10V
excitation and 2mV/V gauge factor will give 20mV when fully loaded.
The meaning of a 20mV output depends on the type of the strain
gauge. If it was designed to measure 0-1000Kg then 20mV indicates a
1000Kg load.
Cleaning
The case can be wiped with a damp cloth. De-energise the unit before
cleaning.
Setup
General
The ACT20P Bridge has internal switch settings that determine
the excitation voltage (5V or 10V) and Input range limits. Select the
appropriate settings from the table below.
Once you have set the DIP switches, you simply calibrate the unit to
the input and output range for your application.
Front panel DIP Switch settings
Switch Action if On Action if Off
110V Excitation 5V Excitation
2mA Output Voltage Output
310mV Span
Turn off for other ranges
420mV Span
530mV Span
650mV Span
7
4-wire Measurement 6-wire Measurement
8
Installation
Caution: These units must only be installed by qualified staff in
accordance with the information given in this manual and all relevant
national electrical wiring and safety rules must be followed.
Locate the instrument in an area that is free from dust, moisture and
corrosive gases. Do not cover the ventilation holes at the side of the
case.
Connections
For effective protection from electromagnetic noise, all signal cables
must be shielded, or located on conductive trays or in conduits.
Strip wires to 7mm from the ends. Use a suitable ferrule for multi-
stranded wires (do not solder).
Power Supply Requirements
Power Supply Ratings are as follows:
Voltage Range Nominal Voltage Power
10 – 60 Vdc 24 Vdc 3 W (at 24 V dc)
Environmental conditions
Relative humidity: 10-90% (non-condensing)
Ambient temperature: -40° to 70°C
[+ Sense]
[+ Excitation]
[− Excitation]
[− Sense]
[− Signal]
[+ Signal]
1321 22 1411 12
ACT20P Bridge
Input connections for ACT20P Bridge with
switches set for 6-Wire measurement
[+ Excitation]
[− Excitation]
[− Signal]
[+ Signal]
21 22 11 12
ACT20P Bridge
Input connections for ACT20P Bridge with
switches set for 4-Wire measurement
Connections
Terminal Signal
11 Signal − Input signal
12 Signal +
13 Sense +
Bridge Excitation Voltage
14 Sense −
21 Excitation +
22 Excitation −
23 Tare + External Tare switch
24 Tare −
41 mA Output −
Output signal
42 Output +
43 mA Test Point −
44 Voltage Output −
44 mA Test Point +
54 +
Power Supply
53 −

ACT20P Bridge
Weidmüller Pty Ltd • 43 Huntingwood Drive, Huntingwood NSW 2148
Technical Support Phone + 61 (0) 2 9671 9999 • Fax [phone]
Email [e-mail] • Web www.mannseries.com
Note: Subject to technical alterations without notice
Printed in Australia • QS610001101 • 08/07/2009Page 2 of 1
Calibration
General
There are three options for calibrating the ACT20P Bridge:
• Bench calibrate using a bridge simulator (if you know the gauge
factor)
• Calibrate on-site by loading the actual installed strain gauge
• Bench calibrate using a mV source (if you know the gauge factor).
Using a bridge simulator
Using a bridge simulator provides the easiest method of calibrating the
unit. Attach as shown. Set values according to simulator instructions.
On-site calibration
On-site calibration can be carried out if you can vary the load on
the strain gauge in a controlled way, so this works best for weighing
devices. Connect up the unit as for a normal installation and use the
unloaded cell and a known load as the calibration points. If you cannot
apply the full load to the device then adjust the full scale output in
proportion to the input load.
For example, if you can only load a 0-1000kg load cell to 500kg and
the required output is 0-10V, set the full scale output to 5V with the
500kg load.
Bench calibration (mV source)
Use the gauge factor to calculate the mV that correspond to the
zero and full-scale loading of the bridge. Apply these values during
calibration. For example, a 0-1000kpa pressure sensor with a gauge
factor of 2mV/V and 10V excitation would have calibration points at
0mV and 16mV for a 0-800kpa measurement range.
Equipment requirements
• A suitable DC Power Supply
• An accurate digital voltmeter to measure the output
• An accurate bridge simulator or millivolt source (not required for on-
site calibration)
Connections for bench calibration (with mV source)
The diagram above shows how to connect up the ACT20P Bridge
for bench calibration using a millivolt source. You should use a Strain
Gauge similar to the one you will be using or a bridge simulator.
Set DIP switch Bits 7 & 8 to the ‘On’ position so that you do not need
to wire the sense leads up. Alternatively you can connect the sense
leads to the bridge in the normal way and set DIP switch Bits 7 & 8 to
the ‘Off’ position. When the calibration is complete remember to return
the switches to their original positions.
Connections for bench calibration (with bridge simulator)
Connect according to the instructions for the bridge calibrator.
Connect the excitation voltage and sense wires to the simulator with a
shielded cable and link the cable drain to terminal 3.
Connections for on-site calibration
Connect up the instrument as you would the final installation.
Calibration Procedure
1. Check that the switch settings are correct for the output type that
you want.
2. Connect up the instrument.
3. Press the UP and DOWN buttons together. The PWR LED and the
‘CAL LO’ LED will both turn red to indicate that you are calibrating the
minimum input and corresponding output low values. [If you want to
skip this stage, press the UP and DOWN buttons together again].
4. Set the input source to the minimum value required, e.g., 0mV for
0-16mV signal.
5. Adjust the output value using the up and down keys until the
multimeter shows the output value required at minimum input, e.g.,
4mA for a 4-20mA output.
Note: For zero based signals, it is important to start with the output
above zero and reduce the output using the down key to just above
zero.
6. When you are satisfied with the output, press the ENT button. The
‘CAL HI’ LED will switch on to indicate that you are calibrating the
maximum input and corresponding output values [If you want to skip
this stage, press the UP and DOWN buttons together again].
7. Set the input source to the maximum value required, e.g., 16mV for
a 0-16mV signal.
8. Adjust the output using the up and down keys until the output is at
the value required at maximum input, e.g., 20mA for a 4-20mA output.
9. When you are happy with the results, press ENT twice. Then
all three LEDs will switch on then turn off. After two seconds the
instrument will return to normal operation (with the PWR LED set to
green). To discard the calibration values, press the UP and DOWN
buttons together.
[+ Excitation]
[− Excitation]
[− Signal]
[+ Signal]
21 22 11 12
ACT20P Bridge
(Set excitation switches to 2-wire)
−+
mV Source
Cal Low Cal High PWR Description Options
Off Off Green Run Mode Press TARE for Tare; or Press [UP & DOWN] for calibration
Red Off Red Low Calibration UP or DOWN to adjust output; ENTER to accept; or Press [UP & DOWN] to skip
Off Red Red High Calibration UP or DOWN to adjust output; ENTER to accept; or Press [UP & DOWN] to skip
Red Red Red Ready to save values ENTER to accept; or Press [UP & DOWN] to discard values
Off Off Off Saving values Last for 2s and unit returns to Run Mode.