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Goals and Symptoms
What protective circuitry is required for Momentum relay output modules when switching inductive loads?
Causes and Fixes
To reduce the effects of radiated noise, it is required that snubbing components be added across inductive load devices.
For AC circuits, rule of thumb is to add a 50 ohm resistor in series with a 0.47microfarad non-polarized capacitor across the load. Minimum component ratings would be 200VAC for 120VAC powered loads and 400VAC for 220VAC powered loads.
For DC circuits, rule of thumb is to add a reverse biased clamping diode across the load. Component rating should
be 2A minimum and greater than twice the maximum load voltage.
Relay and contactor manufacturer catalogs can be consulted for commercial suppression devices matched to their
Units affected are:
170ADM39030 10pt IN/8pt Relay OUT Module Base
170ADM39030C 10pt IN/8pt Relay OUT Module Base Conformally Coated
170ARM37030 24VDC 10pt IN/8pt Relay OUT Module Base (120VAC Powered)
170ARM37030C 24VDC 10pt IN/8pt Relay OUT Module Base (120VAC Powered) Conformally Coated