Are you confident that your relay is detecting proper phase rotation?


The microprocessor-based ES-47 relay compares both positive- and negative-sequence components.

The simple, yet advanced, fundamental sensing ES-47 Phase Sequence Relay can be used on A-B-C (L1-L2-L3) or A-C-B (L1-L3-L2) systems. The relay can be connected directly to systems up to 480 volts or connected through voltage transformers to systems with higher voltages.

Correct phase-sequence operation is ensured when the positive-sequence component is greater than the negative-sequence component, and greater than 75% of the nominal input voltage. The ES-47 energizes the output relay and lights the green "123" LED. A flashing "Power" LED indicates a relay fault.

These advanced calculations provide three key benefits:
  • Ensure proper phase sequence
  • Prevent operation on harmonics quantities
  • Enable detection of a loss of phase or undervoltage condition
For more information about the advanced microprocessor-based features, visit the ES Series Protection Relays page.
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