Can Macromatic's Three-Phase Monitor Relays be used with open delta systems?
Yes, by following a few simple guidelines.
Here is an open delta schematic:
- The phase monitor needs to connect to A,B,C….not GND or Neutral
- Select the correct phase monitor using the Phase to phase voltage of the power system, not Phase to neutral or ground voltages.
- Ensure that Actual Unbalance is within the acceptable range of the phase monitor relay selected for proper operation or use a relay that does not provide unbalance protection. Open delta systems are predisposed to higher levels of unbalance.