EM-20 Logic Relay Mode w/ Long Delay:
is mode shall be used when attempting to combine two air conditioners on one 20A
breaker. ese air conditioners shall be equipped with energy management system inputs
and have the ability to use logic relays for compressor control. THIS MODE SHALL BE
SELECTED IF THE AIR CONDITIONER CONTROL CIRCUITRY DOES NOT PRO-
VIDE THE NECESSARY OFF-TIME DELAY ITSELF TO PREVENT SHORT CYCLING
THE COMPRESSOR.
Power is applied to the EM-20, aer a short delay of approximately 4 seconds, power will
be supplied to both the primary and secondary circuits (also triggering the “OFF time
delay timer” of approximately 3 minutes) and the logic relays will be energized. Both
power relays will continue to stay on for as long as there is power applied to the EM-20.
e control is performed through the logic relays. Once the “OFF time delay timer” has
expired the EM-20 de-energizes the logic relays, and will constantly monitor current
levels, shutting down (energizing) the secondary logic relay when levels reach
approximately 18A. e “o time delay timer” is then triggered. Once the timer has
expired, and the current levels have dropped below approximately 5A, the secondary logic
relay will be de-energized.
EM-20 Logic Relay Operation Detail:
e EM-20 logic relays provide dry relay contacts (simple low current switch closure) and
operate as follows: Under normal operation with both circuits ON, the logic relays will be
de-energized (relay common connected to the normally closed contacts). When the total
current exceeds the upper trip limit, the logic relay for the secondary channel is energized
(relay common connected to the normally open contacts).
For wiring air conditioners with energy management logic capabilities please refer to the
Air Conditioner Logic Wiring section.
EM-20 Remote Control
e EM-20 remote control allows the user to easily specify which circuit should always
remain ON, in the event that appliances on both branches require too much power. e
LEDs indicate which branch will be Primary, allowing the other branch to be shut OFF.
Pushing the button (until a so click is felt) will change the preference. e LED for the
circuit indicating the primary branch will change immediately as soon as the button is
pressed.e background relay activation will occur aer a short delay of approximately 4
seconds.
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