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Portable Phase Angle Meter from 1924 Silent Sentinels

Silent Sentinels 1924 Excerpt #16

This excerpt from the 1924 version of Silent Sentinels discusses how engineers used a phase angle meter in the early days of the electrical system.  What differences can you spot when compared to the phase angle meters used today?

This is the 16th in the series. Follow these links to learn more about this series and the 1924 version of Silent Sentinels.

Westinghouse Protective and Control Relays

Portable Phase Indicator for use in Making Relay Connections


In order to obtain correct operation when connecting a relay, which requires both current and voltage connections, to a polyphase circuit, it is necessary to select the current and voltage having the proper phase relation to each other. One of the most convenient methods of checking such relay connections is to use a Westinghouse Phase Indicator.

The phase indicator shown in Figure 144 is a portable instrument built on the same principle as is a power factor meter. However the phase indicator is calibrated to indicate degrees, from 0 to 360, instead of power-factor percentages. It readily shows the exact phase relation between any current and voltage to which it may be connected.

The phase indicator can also be used to check the phase relation between two or more currents. An example of such an application is the checking of relay connections for differential protection. To select the two current transformers the secondaries of which should be connected together, it is necessary only to select some voltage for use as a reference, and then to measure the phase relation of the different currents with respect to this reference voltage.

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About the Author

Chris is an Electrical Engineering Technologist, a Journeyman Power System Electrician, and a Professional Engineer. He is also the Author of The Relay Testing Handbook series and founder of Valence Electrical Training Services. You can find out more about Chris here.

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  1. Chris,
    We were still using same meter pictured in 2005 when I worked for utility
    There were still questions regarding the new digital meters and digital relays
    Most utilities are slow to allow new technology and I see ‘IT’ groups trying to control the protective relays do to computer like programming, communications and NERC security issues, however they rarely have the necessary background or training putting the system in jeopardy
    When the system crashes call me I’ll bring the old Westinghouse phase angle meter!!!!!!!!!!!!

    1. Very cool! My problem with modern phase angle meters is that there are no pictures. 120 and 240 degrees are not fixed terms and can mean the opposite depending on the equipment manufacturer. There’s no confusion when we can see where the angle is instead of guessing.

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