Measurement of phase/phase-to-phase voltage & line current using single voltmeter and ammeter

Ammeter Selector Switch
Voltmeter Selector Switch


In most of the industrial applications, electricity is distributed in three phases i.e. R-Y-B (L1-L2-L3) system. Heavy industrial loads like motors, air compressors, work on three phase supply; Thus, electrical control panels are installed for controlling and monitoring of the electrical parameters of the system. In these panels, analog meters are generally deployed for measurement and monitoring of current and voltage levels of the installed system. This also helps to ensure that the three phase system is balanced.

Problem Statement

In a three-phase system, in order to monitor current in each line, separate ammeters have to be used in each line. Similarly, for phase and phase to phase voltage measurement, separate voltmeters have to be used. For this, individual meters are installed that occupy more space and increase the cost of installation.


Rish Selector Switch

The basic idea behind the use of a selector switch is to reduce the number of panel meters used to monitor currents and voltage of the installed system.

As replicated in the diagram below, the Voltmeter Selector Switch can be connected between a Voltmeter and the three phase line. Whenever the user needs to measure the voltage of a particular phase, the switch position could be changed to any one of the desired position i.e. “RY” “YB”, or “BR”. The respective phase voltage will be displayed on the Analog voltmeter

Similarly, in case of Ammeter Selector Switch, the respective line current can be measured on the Ammeter by switching the switch position from “OFF” to “R”, “Y” & “B”

Using this solution, a single analog meter can be used to monitor the parameter of a three phase system which contributes to a cost effective solution with better aesthetics.

Other applications areas:

  • Industrial Panel 
  • Motor Controls 
  • Coolant Pumps

Available features

  • Compact Size & Reliable Design
  • Multi pole design with multiple stacks
  • Quick and Easy Installation
  • High Protection Class :IP 50