videogeniX uSwitch, Installation And Operating Manual

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uSwitch and uSwitchPro Installation and Operating Manual Page 34
Connecting to High Power devices (such as Motors, etc)
For loads greater than those rated for the uSwitch’s internal relays, or when connected to devices with high inrush or peak
current surge an external relay should be used with the uSwitch triggering the relay. The illustration below shows how a
high current motor or other high load device can be controlled using by wiring to an external relay. A variety of external
relays is available and can be ordered either online or directly from Videogenix.
When relays switch inductive loads such as motors, transformers, relays, etc., electricity will arc across the internal relay
contacts each time the contacts open. Over time this causes wear on the relay contacts which can shorten their life span.
When switching a high inductive load, it is recommended that simple relay contact protection devices be used. To be
economically feasible uSwitch cannot provide relay protection for all possible loads.
For applications with excessive loads, the following diagram shows a relay contact protection circuit for DC and for AC
applications. For component values required to provide sufficient contact protection for a specific application, consult the
application reference. Note: for DC circuits a diode is used and for AC circuits an RC circuit across the load can be used.
Connection to an External Relay