IAI America PDR-101-MW - Manual (Page 21)

11
(3) Protecting Against Noise Emitting Sources
There are many types of noise emitting sources, but the most familiar ones when building a system
include solenoid valves, magnet switches and relays. The controller can be protected against noise
from such sources by the following actions:
a. AC solenoid valves, magnet switches and relays
Action: Mount a surge killer in parallel with each coil
b. DC solenoid valves, magnet switches and relays
Action: Mount a diode in parallel with each coil. Determine the capacity of the diode according to the load
capacity.
Careful attention should be paid in the case of DC current; if
the polarity of the diode is mistaken, the diode, internal circuitry
of the controller and/or DC power supply may be destroyed.
← Point
Connect the surge killer to each coil with the shortest
possible wiring.
When it is connected to a terminal block or similar,
the effect is lost if the distance to coil is large.