What is a 4-20mA loop splitter?
This device is designed to split a single 4-20mA input signal into more than two separate non-isolated 4-20mA current loop outputs which mirror the input.
For each output channel, separate calibration adjustments are provided that can be used to independently change the output spans. The outputs can share a common ground.
Why loop splitters are used?
Multiple series devices such as panel meters, chart recorders and PLCs receive the same 4-20 mA signal from the transmitter. If any device in the loop is removed, fails or fails to cable, all other devices will lose their 4-20 mA signal as well.
Sources up to four (4) independently adjustable outputs of 4-20 mA from a single input, 4-20 mA, 1-5V, 0-5V or 0-10V, as selected by jumpers.
Common ground for input and output
Each loop drives only one load, thereby avoiding problems with voltage compliance.
Power can be 85-264 Vac or 10-48 Vdc or 12-32 Vac (varying from model to model) for the loop splitter. On the input side of the signal, an excitation output is provided to drive a 2- or 3-wire transmitter up to 30 mA at 24 Vdc.
Loop splitter electrical connection:
Current output (Pin 1) and current return (Pin 2) can be connected to any output load R that is floating (not connected to a local ground or earth ground). The current return is internally linked to the ground signal SG, which can be floated or connected to the ground.
All circuit boundaries between devices must be connected as closely as possible with connections between devices and any other wiring associated with this device.
Loop splitter calibration:
The zero and span of the four output loops (L1, L2, L3, L4) are set to precise 25-turn potentiometers marked on the front panel with Z (for zero) and S (for span). The unit is jumpered and calibrated factory so that 4-20 mA in all output channels produces 4-20 mA output.
Apply the low input signal (4 mA, 0V or 1V) that should produce the low output of 4 mA to set or calibrate an output channel. Measure the actual output (for example, 4,218 mA). Then apply the high input signal (20 mA, 5V or 10V) to produce a high output of 20 mA.
Adjust the zero and span to correct the corresponding response.