Modes of Operation
EM-15 Power Relay Mode:
e EM-15 has a single mode of operation for the following application: sharing the
power between two appliances on a 15A breaker (for example: a microwave and a replace
or water heater).
is mode of operation functions as follows: Power is applied to the EM-15. Aer a short
delay of approximately 4 seconds, power will be supplied to both the primary and sec-
ondary circuits. e EM-15 constantly monitors current levels, and will shut down the
secondary circuit once levels reach approximately 13.5A. Once the current levels have
dropped below approximately 5A, power will return to the secondary circuit.
EM-20 Modes:
e EM-20 has 4 basic modes of operation.
1. Power Relay Mode w/ Short Delay
2. Power Relay Mode w/ Long Delay
3. Logic Relay Mode w/ Short Delay
4. Logic Relay Mode w/ Long Delay
e mode can be switched using the red & white switch located inside the EM-20. If the
mode is changed it will require the power to be cycled OFF then ON before the EM-20
will recognize the new mode. e EM-20 implements these modes through 4 dierent
internal relays (2 high current power relays and 2 low current logic relays).
Power Relay vs Logic Relay:
In Power Relay Mode, when faced with an over current condition, the power for the entire
secondary circuit shuts OFF.
In Logic Relay Mode, when faced with an over current condition, the power for the
secondary circuit always remains ON, while a “logic relay” switches states.
Logic Relay Mode expects the load to manage its’ own power. is is a very important
distinction! Logic Relay Mode shall NOT be used unless the load is designed to be used
with an energy management system, and has inputs which expect a simple, low power
relay switch closure.
Long Delay:
When an air conditioner is in operation, its compressor circulates refrigerant under high
pressure. Once OFF, it will take 2-3 minutes for this high pressure to equalize. For this
reason, the EM-20 adds an o-time delay of approximately 3 minutes. is delay will
prevent “short cycling” the compressor and will also be observable during the initial
power ON sequence of the EM-20.
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