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Relays
In commercial operators, relays are often used to either control
certain operator functions or activate/deactivate ancillary devices
such as heaters or lights.
When electricity is applied to a relay coil, it energizes a magnet and
will close a Normally Open switch or open a Normally Closed switch.
A relay typically has prongs labeled Comm, NO, NC, and two prongs
to power the relay coil. See the light circuit example below containing
a relay.
When the NO switch is pressed closed, electricity will travel through the relay coil and activate the relay. The relay
switch will allow electricity to fl ow through the circuit and turn on the light.
An “Ice Cube” relay
NO Switch
Comm NO NC
Light Bulb
Battery
Relay
12V 24V
D
Basic Electrical Information
Relays
The diagram below shows two different batteries supplying different voltages. The relay separates the electricity so the
different components are able to work together. Commercial door operators work in a similar fashion. Relays make it
possible for high voltage to work with low voltage.
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