eMon Energy Monitor can handle any size electrical system. It is Single (most residential buildings) and Three Phase (most larger businesses and Hotels) compatible. Users can choose between two methods to measure Three Phase Voltage:

Derived Reference uses a single voltage transformer and derives a reference voltage/phase for the other two phases by numerically shifting the phase of the single reference by 120° or 240°. The primary advantage is low cost and convenience of installation. The disadvantage is that large variations in voltage between phases may result in decreased accuracy.

Direct Reference uses three discrete voltage transformers or VTs, each one plugged into a circuit on a different phase. The primary advantage is voltage accuracy, while the disadvantages are that the extra VTs add cost, require using two of the inputs, and require plugs on each phase in proximity to the eMon Energy device.

A prime component of electrical power is voltage. The AC line frequency is the heartbeat of the eMon Energy. A reliable and accurate AC voltage reference is very important. You should have installed the device with a 9 Volt AC voltage reference transformer (VT) plugged into the channel zero power jack. If your initial configuration has this channel pre-configured, your LED will be glowing green because it’s rhythmically sampling that voltage.