© Agrowtek Inc. | www.agrowtek.com | Technology to Help You Grow™
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How “Dry-Contact” Relays Work
A relay consists of a mechanical switch and
an electro-magnet to turn-on (close) a switch
contact. A spring opens the switch when the
electromagnet is no longer powered.
The microprocessor controls power to the
magnet coil to open or close the switch con-
tact as required by the controller program.
Dry-contact relays can be thought of like a wall-switch:
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Each relay “contact” has a pair of screw terminals just like a wall-switch does.
•
A wall-switch (or relay contact) does not supply power, it only allows it through.
•
Each switch is independent and can operate different circuits or voltages.
Many types of devices can be operated with a dry-contact switch. A dry-contact interface allows Agrowtek
controls to integrate with building controls, high amperage loads and other custom devices such as:
What Relays Control
A dry-contact relay is exactly the same as a wall switch, however, instead of operating the switch manu-
ally with your finger, an electromagnet operates the switch.
High-Amp
Relays & Contactors
HVAC Control
Irrigation / Gas
Solenoids
120V Receptacles
& Equipment
Introduction
GrowControl RD series dry-contact relays interface Agrowtek’s intelligent controllers to devices in your grow-
ing environment to control lighting, ventilation, irrigation, HVAC and much more. Dry-contacts allow many
different types of equipment to be controlled.
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Magnet
OFF
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Magnet
ON
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Controller
Voltage
Magnet Coil
Electro-Magnet
Switch Contact
Power Out Terminal
Power In Terminal
Switch Actuator
