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Interfacing a PUMC SM/SMP servo with a Powerflame DC-4 Draft Controller

FILED UNDER: Actuators, SMP Servo


Customer or service guy needs to interface a PU SM or SMP servo with a Powerflame DC-4 Draft Controller

Steps to Troubleshoot

This requires modifying Powerflame's existing panel wiring to work properly.  In the case of a Powerflame DC-4 with Honeywell actuators, the actuator itself has a 24Vac power supply that brings power to terminal R.  When the PLC inside the cabinet needs to either increase or decrease draft, it activates relays on either Q0.0 (close) or Q0.1 (open).  The PLC outputs are wired to panel terminals W and B, respectively, with the neutral wired to panel terminal R.  The PLC doesn't use any position feedback from the actuator.

To wire one of our SM servos take the following steps:

1) Jumper R to 1F in the panel.  This brings 120Vac to the relays

2) Wire panel terminal 2 to SM actuator terminal 1 for the neutral line

3) Wire panel terminal W to SM actuator terminal 2 to close the damper

4) Wire panel terminal B to SM actuator terminal 3 to open the damper

In the event that an SMP actuator has been supplied rather than an SM, simply wire the panel terminals directly to the servo terminals below the board

The Powerflame DC-4 also requires limit switches to verify the damper is in purge position and start position:

1) The damper purge switch is across terminals E5 and E6, and is wired normally open.  Wire to the appropriate external limit switch using terminals 13 and 14.

2) The damper start switch is across terminals LF1 and LF2 and is wired normally closed.  Wire to the appropriate external limit switch using terminals 21 and 22


Verify the damper strokes open and closed by using the Open/Close/Auto switch on the top of the panel.