Rockwell Automation 1771-PM , D17716.5.18 U MNL 1771-PM CLUTCH/BRAKE MOD - Manual (Page 63)

Field Wiring Arm Connections
Chapter 6
6Ć11
Each solenoid valve should draw at least 60mA. If not, connect an
appropriate load resistor in parallel with it. For neatness and safety, we
recommend that you connect feedback and load resistors only at
convenient terminal strips, not at the field wiring arms.
Select the same type of solenoid valve for micro-inch as you select for
main and auxiliary solenoid valves (internal or external fault detection).
Use series C or later 1771-OD output modules because they have
improved electrical noise immunity.
To provide additional immunity against surge transient noise, we
recommend that you connect metal oxide varistors (MOVs) to the triac
outputs of your 1771-OD modules for main and auxiliary valve solenoids,
and dump valve solenoids, if used. Typical connections are shown for
auxiliary valve solenoids for ungrounded AC power (Figure 6.4)) and
grounded AC power (Figure 6.8). Connect the MOVs as close to the field
wiring arm terminals as possible. In the grounded AC power
configuration, make connections to 3L2 (not located on the field wiring
arm) as short as possible.
Electrical Noise Suppression