Universal Strain Gauge Bridge Input Transmitter

The STRAIN Universal Strain Gauge Bridge Input Transmitter is a versatile and reliable solution for converting signals from strain gauges, load cells, and pressure transducers into standardized outputs. With its high-stability excitation voltage and user-friendly calibration options, the STRAIN simplifies the setup and integration of strain measurement systems. Whether you need 0-10Vdc, 0-20mA, or 4-20mA output, the STRAIN delivers precise signal conversion with options for both low and high voltage power supply.

Contents

Key Product Features

Internal excitation voltage: The STRAIN provides an internal 10Vdc (or other factory-set values) excitation voltage for powering the sensor, eliminating the need for external power supplies. It’s a key feature that distinguishes the STRAIN from the ISOCON.
Compatibility with different load cell sensitivities: The STRAIN can be configured to work with various load cell sensitivities, including 1 to 3 mV/V and 6 mV/V. It can be custom calibrated to match the specific output characteristics of different load cells.
Signal conversion accuracy: The STRAIN boasts high signal conversion accuracy, typically within 0.1% of full scale at room temperature.
Output options: Users can select either 4-20mA or 0-10Vdc as the output signal, depending on the requirements of their data acquisition system. This can be set up in the factory or configured by the user following the instructions in the manual.
Power supply versions: The STRAIN is available in two versions: one that operates on 240Vac power and another that uses 28Vdc. There are no other differences between the two versions.
Custom modifications: The manufacturer can provide custom modifications to the STRAIN to meet specific user requirements. For example, the STRAIN-DUAL can be modified to convert bipolar signals.

Product Description

The STRAIN universal strain gage bridge input transmitter is suitable for use with the majority of strain gauges, load cells and pressure transducers. The unit provides a high stability excitation voltage which is isolated from both the high level output and the power supply.

Front panel push buttons allow non-interactive adjustment of the output zero and span settings. This is especially useful for the initial calibration and set-up of the bridge and measuring system.

The output required may be user-reconfigurable using internal switches or requested at point of order. The options include 0-10V dc, 0-20mA, and 4-20mA. It has two power supply options, operating either from a 10 to 36Vdc supply or 90 to 264Vac supply.

The unit is housed in a 12.5mm DIN rail mounted enclosure.

Front panel mounted zero and span potentiometers can be used for in-field adjustment, used in conjunction with the output monitoring pins which allow the output to be measured without breaking the current loop.

Power supply options are either 12-36Vdc or 90-262Vac.

Two versions are available, the STRAIN-6 with a 12-36Vdc supply or the STRAIN-3 with a 90-264 Vac supply.

Product Types

STRAIN-6

SKU ID: s1-strain-0001
New Part No: II-STRAIN-6-JJ-J-000
Old Part No: II-STRAIN-JJ-6-00-00
Input Types: 0-25mV…0-1200mV, unipolar or bipolar, switch selectable
Input Sensor Supply: 10Vdc
Output Types: 4-20mA, 0-20mA, 0-10mA, 2-10mA, 2-10V, 0-10V, 0-5V, 1-5V – mA source/sink, sqrt extraction, switch selectable
Power Supply: 12-36Vdc, typical 24Vdc, 12-32Vac
Isolation: Full 3-Port
Installation Type: DIN Rail TS35
Electrical Connections: Screw clamp with pressure plate

STRAIN-3

SKU ID: s1-strain-0002
New Part No: II-STRAIN-3-JJ-J-000
Old Part No: II-STRAIN-JJ-3-00-00
Input Types: 0-25mV…0-1200mV, unipolar or bipolar, switch selectable
Input Sensor Supply: 10Vdc
Output Types: 4-20mA, 0-20mA, 0-10mA, 2-10mA, 2-10V, 0-10V, 0-5V, 1-5V – mA source/sink, sqrt extraction, switch selectable
Power Supply: 90-264Vac
Isolation: Full 3-Port
Installation Type: DIN Rail TS35
Electrical Connections: Screw clamp with pressure plate

Pre-configured Millivolt Input Signal Converters

Choose a pre-configured STRAIN which is set-up for a specific fixed millivolt range input and output signal:

0 to 100 millivolts signal converters

Signal converters for 0 to 100 mV scale inputs & outputs.

0 to 50 millivolts signal converters

Signal converters for 0 to 50 mV scale inputs & outputs.

0 to 30 millivolts signal converters

Signal converters for 0 to 30 mV scale inputs & outputs.

0 to 20 millivolts signal converters

Signal converters for 0 to 20 mV scale inputs & outputs.

Product Help

Internal or external strain gauge supply voltage

Do we need to connect a 10Vdc power supply to terminals 3 and 6, or does the strain gauge transmitter have the 10Vdc supply internally in those terminals to connect to the sensor?

The supply is internal, it’s one of the main features that distinguishes the STRAIN from the ISOCON which it is derived from, it has a factory set sensor excitation voltage supply for powering the sensor, the default setting is 10Vdc, but it can be set in the factory to another value such as 5Vdc if needed instead.

Pressure divided by multiple load cells on hydraulic press

We have a test press that is capable of applying 20000psi of force and is large enough to accommodate 4 load cells at once. With that said, my first test was to try each loadcell individually. I applied 2000, 2500, 3000, and 3500 to each load cell. Each load cell was within 20% of the applied psi (they were not yet calibrated for zero or span). After individual testing I thought I could save some time by zeroing and spanning them at the same time. So, I placed 4 load cells on the tester and applied 10000 psi. Each of the load cells readings were between 2000-2500 psi. I confirmed that the test press was accurately applying the correct pressure. I then decided to try just 2 loadcells, this time I applied 2500 psi, and the load was split between the 2 load cells, with each reading approximately 1250 psi. Why is it dividing the pressure across all the load cells? Am I right to assume that the pressure should be applied equally to all the load cells? If so, shouldn’t I see 10000 psi on all 4 Loadcells for the first test, and 2500 psi on each of the 2 load cells for the second test?

That is all working as it should, but load cells are actually measuring the resulting force produced by the piston not the hydraulic pressure inside the cylinder. The pressure generated inside the test press piston/cylinder is transferred to the piston as a force. When you apply this force to more than one load cell, it will be shared between each load cell, so the more load cells you add the less force they will read, for the same pressure generated by the press.

1 to 3 mV/V load cells

Would we be able to use this signal converter to generate a 0 to 10 volt output signal on a load cell with a 1 to 3 mV/V sensitivity, for example a 2.96 mV/V load cell will will provide 29.6 millivolt signal at full load when excited with 10 volts?

Yes, as standard the sensor bridge excitation voltage for the mV input will be set to a fixed 10Vdc to provide a stable 0 to 30 mV input.

It will be custom calibrated for a 0-30mV input to 0-10Vdc output, so any deviation between sensors will require the operator tweak the calibration of each STRAIN device e.g. 0…29.6 mV to 0…10Vdc.

Two load cell inputs to one output

Can this millivolt signal converter accept two load cell mV inputs and return a single output?

The STRAIN is a single input device, but it is common to connect up two or more load cells into a parallel configuration which will produce a single averaged output for all the load cells. The connecting together of the load cells into a parallel configuration is simplified by using what is called a ‘load cell junction box’ between the load cells and a signal conditioning module such as the STRAIN.

Signal conversion accuracy

What sort of error would the unit give at say 50% of input range?

The signal conversion error will be within 0.1% full scale at room temperature.

4-20mA or 0-10Vdc DAC input

Our DAQ system can accept 4-20mA or 0-10Vdc signals, will this strain gauge input converter provide one of these signals as the output?

Both are possible, you can select either 4-20ma or 0-10vdc following the instructions in the manual, or you can request this to be setup in the factory if you specify the configuration required when ordering.

Power supply version differences

Any advantages of using either the 240Vac or 28Vdc version?

There is no other differences between the -6 and -3 versions other than the required power supply.

6mV/V load cell compatibility

We have two two tension type load cells with 6mV/V span sensitivity and 100k lbs range, and the excitation supply voltage currently applied is 10vdc, will this signal converter work with these load cells?

Yes, an input range of 0-60mV input with a 10Vdc supply will be fine. There is a bridge excitation voltage available also for powering the load cells if you need it, which is set to 10Vdc as standard.

2 load cells with 2KΩ output resistance in parallel

We are planning to connect 2 load cells in parallel. Load cell output resistance will be 2000 ohms for both load cells, and the output signal will be 2mV/V, will the STRAIN work with this set-up?

Yes the STRAIN will work the characteristics and configuration you have described.

Load cell mV signal to 4-20mA output

We are planning to connect a load cell output (mv/V) to this device and require a 4-20mA output. Also we need fine tuning pots to calibrate the output signal?

The STRAIN is calibration by using push buttons on the front panel to fine tune, and internal switches for coarse range adjustment.

SKU ID: s1-strain-0003
New Part No: II-STRAIN-6-AA-A-000
Input Types: 0-25mV…0-1200mV, unipolar or biploar, switch selectable
Input Sensor Supply: 10Vdc
Output Types: 4-20mA – mA source/sink, sqrt extraction, switch selectable
Power Supply: 12-36Vdc, typical 24Vdc, 12-32Vac
Isolation: Full 3-Port
Installation Type: DIN Rail TS35
Electrical Connections: Screw clamp with pressure plate

Bipolar ±50mVdc input to ±4Vdc output converter

I need a signal converter that will accept a +/-50 mVoltdc and gives a +/-4Vdc output?

The STRAIN-DUAL (dual output version of the STRAIN millivolt input converter) with some custom modification, will allow you to convert a bipolar +/-50mV input to a bipolar +/-4Vdc output. Both outputs would be set-up as 0-20mA with one inverted, and then feed both into a 500Ω resistor, and then adjust the output to give +/-4 Vdc.

SKU ID: s1-straindual-2-6445
Part No: II-DCON-STRAIN-6-AJ-JJ-000
Input Types: -50 to +50mV
Input Sensor Supply: 10Vdc
Output Types: -4 to +4Vdc
Power Supply: 16-36Vdc, typical 24Vdc, 18-32Vac
Isolation: Full 3-Port
Installation Type: DIN Rail TS35
Electrical Connections: Screw clamp with pressure plate

Bridge supply & connections

Looking at the product manual I can’t find a section on setting up bridge supply, do you use connection 3 & 6 for the bridge supply, and how do you change bridge supply voltage?

It is connection 3&6 that is used, but the excitation voltage is factory set, usually at 10Vdc.

2.5mV/V Gefran sensor

I want to convert a 2.5 mV/V Gefran sensor to a 4-20 ma signal?

Yes you can use the STRAIN to convert your Gefran sensor, you can select an input of 0-25mV and utilise the 10 volt dc internal sensor power supply to operate the sensor without needing to use of any other electronics.

2mV/V @10V to 0…10mA conversion

I’m looking for a device that will convert a bridge out signal of 2mV/V with a bridge excitation of 10 Vdc to a 0-10mA output signal?

We would the suggest the following STRAIN configuration to provide a 0…20mV to 0 to 10mA signal conversion:

SKU ID: s1-strain-0004
Input Types: 0 to 20mV
Input Sensor Supply: 10Vdc
Output Types: 0-10mA source/sink
Power Supply: 90-264Vac
Isolation: Full 3-Port
Installation Type: DIN Rail TS35
Electrical Connections: Screw clamp with pressure plate

Solar irradiance sensor with 0-75mV output

I need an amplificator that will accept an input signal from a solar irradiance sensor of min 0 mV & max 75mV and has an output signal of min 0V max 10V or 4-20mA so that it can be sent to a plc input?

We would suggest the STRAIN which can be set up to accept a range of millivolt inputs which includes 0-75mV, and convert this to an amplified 0-10 volts or 4-20 milliamp current output. The s1-strain-0001 will work from a low voltage supply ac/dc, and the s1-strain-0002 will work from high voltage mains ac.

Universal Strain Gauge Bridge Input Transmitter – STRAIN