The 420i 4-20mA loop powered isolator is typically used to provide an isolated 4-20mA current loop from any existing 4-20mA loop. This isolated 4-20mA can then be connected to any input stage without affecting other signals connected to the same earth. The output can be connected to any potential within 1kV of the input negative terminal while transients of 2.5kV can be withstood.
- Isolated 4-20mA output
- Loop powered
- Low Voltage drop
- High Accuracy, better than 0.1%
- 1kV Isolation
Product Description
The 420i loop powered isolator is a 0(4)-20mA direct current isolator. The isolator derives its power from the input signal and therefore requires no external power supply.
The output of the isolator is typically used to enable two control and instrumentation devices, e.g. PLC and local chart recorder, with non-isolated inputs, to monitor the same transmitter output simultaneously.
Alternatively the isolator can be used to isolate signals from non-isolated transmitters or as a noise reduction device.
Two variants are available. The 420i-1 which has a built in precision 250Ω resistor to give a 1-5V output, and the 420V which gives a 0-10V output from a 4-20mA input, whilst dropping just 5V from the input loop.
Another typical application is to use the 420i to enable two instruments to monitor the same 4-20mA at the same time. The 420i is wired in series with the input of the first instrument and then the output wired to the second.
The 420i also acts as a noise reduction device, giving a ‘clean’ 4-20mA output.
Isolator Types
420i 4-20mA out
4 to 20 milliamp isolated output signal
- SKU ID: s1-420i-0001
- Part No: II-420i-AA-8-000
- Input Signal: 4-20mA
- Output Signal: 4-20mA
- Power Supply: Loop powered
- Installation: DIN Rail TS35
- Electrical Connections: Screw clamp with pressure plate
420i 1-5V out
1 to 5 volt dc isolated output signal
- SKU ID: s1-420i-0002
- Part No: II-420i-AF-8-000
- Input Signal: 4-20mA
- Output Signal: 1-5Vdc
- Power Supply: Loop powered
- Installation: DIN Rail TS35
- Electrical Connections: Screw clamp with pressure plate
420V 0-5V out
0 to 10 volt dc isolated output signal
- SKU ID: s1-420v-0003
- Part No: II-420V-AE-8-000
- Input Signal: 4-20mA
- Output Signal: 0-5Vdc
- Power Supply: Loop powered
- Installation: DIN Rail TS35
- Electrical Connections: Screw clamp with pressure plate
420V 0-10V out
0 to 10 volt dc isolated output signal
- SKU ID: s1-420v-0004
- Part No: II-420V-AG-8-000
- Input Signal: 4-20mA
- Output Signal: 0-10Vdc
- Power Supply: Loop powered
- Installation: DIN Rail TS35
- Electrical Connections: Screw clamp with pressure plate
Product Help
Low input loop current
I’m trying to use this with a 4-20mA sensor connected to two meters. When I put 8mA through the input source from a process calibrator with a multimeter in series, the current drops to 0.5mA. I don’t have anything connected to the output yet. Why doesn’t the multimeter read 8mA?
If you short the output you should see the input current go to 8mA.
Power supply source
How is the 420i output powered? does it take power from the input loop or do you have to provide another power source to the output loop as well?
The 420i obtains its power from the input 4-20mA loop.
Output power source
How is the output powered, does the 420i power the output 4-20mA or is that sink mode so you need to provide an external power supply?
The output is powered from the input loop via the transformer.
Connecting two readouts
I would like to connect two separate readouts together to read the same 4-20mA output, how should the 4-20mA loop be powered for each readout?
The 420i derives its power from the input 4-20mA loop. You would first connect the 420i in series with the current loop for the 1st readout. Since the 420i is not separately powered, the input current will need to be powered either by the readout or some other loop power source.
The output of the 420i can then be connected to the 2nd readout, and it should be configured in sink mode since the loop power will be provided by the input loop via the internal transformer.