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Example 2 – Blower Relay Contact (Three Phase AC)
The Blower set of contacts (Relay 1, pins 2 & 3) will indicate when the cabinet’s blower is on.
On an A2 cabinet, this contact will close once the blower key is pressed on the cabinet’s
keypad, and remain closed while the blower is at Normal Speed.
However, on a B2 cabinet, the contacts will close when the blower key is pressed to signal
(through this Relay 1 contact) a remote exhaust blower to start. The cabinet’s blower will NOT
start until the internal Airflow Sensor verifies proper exhaust airflow from the remote exhaust
blower. Once the blower successfully starts, the contact will remain closed.
The generalized circuit shown below indicates how to interface the cabinet’s provided contacts
to power a Three Phase high current device (like a remote exhaust blower). Note that the
cabinet’s provided contacts are used to actuate the low-power coil of a user-supplied
external power relay/contactor. Never run high current or AC voltage through the
cabinet’s provided contacts!
The relay in the example below is: Potter & Brumfield P25P42D22P1-12, the 12V coil draws
.35Amps (the provided +12VDC is fused at 0.5 Amps total, so choose a relay with an amp draw
for the actuator coil less than 0.5 A). If using all three provided relay contacts, the sum total
of all current draw from three relay actuator coils must be less than 0.5A.
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