• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
SensorsONE

SensorsONE

  • Products
  • Search
  • Contact

4-20mA Max. Load Resistance, Min. Tx and Power Supply Calculator

Calculate 4-20mA Min. Supply & Max. Load
Select Answer Mode
Min. Tx Supply [?]

volts (V)

Max. Load Resistance [?]

ohms (Ω)

Min. Power Supply [?]

volts (V)

Click save settings to reload page with unique web page address for bookmarking and sharing the current tool settings

✕ clear settings



Featured 4 to 20ma signal products

  • Differential Pressure Transmitters - Differential pressure transmitters for measuring the DP of fluids and gases across particle filters and along a length of pipe to monitor flow.
  • 200m deep well pump water level sensor, switch & display - Protect your deep well pump with thhis submersible level transmitter and wall mounted indicator and alarm. This system provides reliable water level monitoring and pump protection at depths of up to 200 meters.

Related Tools

  • 4 to 20 mA Supply, Load, Shunt and Signal Calculator
  • 4-20mA Signal to Measurement Reading Converter
  • DP Flow Transmitter Output Calculator
  • Flow Transmitter 4-20mA Current Output Calculator
  • Liquid Level Transmitter 4-20mA Current Output Calculator
  • Pressure Transmitter 4-20mA Current Output Calculator
  • SqRt Extraction 4-20mA Signal to Measurement Reading Converter
  • Temperature Transmitter 4-20mA Current Output Calculator

Contents

Toggle
  • User Guide
    • Formulas
      • Symbols
    • Parameters
      • Minimum Transmitter Supply Voltage (VminTx)
      • Maximum Load Resistance (RmaxL)
      • Minimum Power Supply Voltage (VminPS)

User Guide

This tool will calculate the maximum load resistance, minimum power supply or transmitter supply that can be used, in order for a 4 to 20mA current loop circuit to have sufficient power to operate.

Determine the lowest voltage power supply that you will be able to use with a 4-20mA current loop circuit by entering the total load resistance in the loop, and the specified manufacturer’s minimum supply voltage for the transmitter.

If you know what power supply you have available, and what transmitter you want to use, you can determine the maximum load resistance that will be allowed in the circuit without affecting the performance of the transmitter.

You can use this tool to determine what transmitter can be used, based on the minimum required supply voltage to maintain a 4-20mA signal over the 0 to 100% full scale measurable range.

4-20mA current loop signal circuit

Formulas

The formulas used by this 4-20 mA maximum load, minimum transmitter and power supply calculator to determine each individual parameter is as follows:

VminTx = VminPS – (I20mA · RmaxL)

RmaxL = (VminPS – VminTx ) / I20mA

VminPS = VminTx  + (I20mA · RmaxL)

Symbols

  • VminTx = Lowest allowed transmitter supply voltage
  • RmaxL = Maximum allowed load resistance of current loop circuit
  • VminPS = Lowest required power supply voltage
  • I20mA = Highest current signal of 20mA

Parameters

Minimum Transmitter Supply Voltage (VminTx)

This is the minimum supply voltage in volts (V) that is required or available to power the transmitter and maintain a 4-20mA signal.

Maximum Load Resistance (RmaxL)

This is the maximum load resistance specified in ohms (Ω) that can be added in series to the power supply and transmitter without affecting the operation of the current loop circuit.

Minimum Power Supply Voltage (VminPS)

This is the minimum voltage measured in volts (V) which is required or provided to power the current loop circuit and produce a 4-20mA signal.

Featured 4 to 20ma signal products

  • DMP331 Precision Pressure Transmitter - Stainless steel pressure transmitter with ranges from 100mbar up to 40 bar gauge or absolute. Special options for ATEX , SIL2 and compound ranges.
  • Vacuum Pressure Transmitters - Choose vacuum pressure transmitters for measurements over the low vacuum range of 25 to 760 Torr, using a absolute or negative gauge reference vacuum range.

Primary Sidebar

Tools

  • Unit Converters
  • Pressure
  • Liquid Level
  • Temperature & Heat
  • Electrical & Electromagnetic
  • Flow
  • Force, Load & Torque
  • Mass & Weight
  • Dimensions
  • Density
  • Time & Frequency
  • Speed & Acceleration
  • Energy & Power
  • Sensors & Instrumentation
  • Shapes
  • Movement & Motion
  • Travel & Transportation
  • Pricing & Quantities
  • Chemical Quantities
  • Health & Fitness

Tool Feedback

Please provide feedback on using this 4-20mA Max. Load Resistance, Min. Tx and Power Supply Calculator.

Measurement Instrument Specifier

Specify a measurement instrument

Select your measurement instrument requirements

Wirelessly Measure & Log 4-20mA

Use this battery powered wireless 4-20mA wireless transmitter to transmit readings to a receiver connected to USB, RS485, RS232, cellular network or analog output

Use this battery powered 4-20mA wireless transmitter to transmit readings to a receiver connected to USB, RS485, RS232, cellular network or analog output
By clicking "OK" or continuing to use this website you are providing your consent to use cookies as described in our Privacy Policy

© 2025 SensorsONE Ltd, all rights reserved

  • Home
  • Products
  • Tools
  • Legal
  • Contact