The following product line is being discontinued. A recommended replacement is shown at:

4-20mA contactor

Potentiometer input, 25 or 40 amp, din rail power controller


  • Allows a customer to dial in a request from 0% to 100% power.
  • Accepts a standard potentiometer input and provides a high speed, time proportional AC output (TPO). That is a zero-crossing, "no electronic noise", power control signal that is ideal for resistive heaters, heat sealing bars, injection molding nozzle zones, simple cookers, etc.
  • Output cycle time ("ON" time + "OFF" time) = approximately 0.5 second at 50%. Output resolution is one half of one sinewave (8.3 msec for 60 hz applications).

Note: Rapid pulsing of the heaters provides the most precise temperature control, PLUS it dramatically increases the life of the heaters due to a reduction in the thermal stress of expansion and contraction.

  • A standard 0-5k potentiometer can be mounted anywhere on the machine.
  • Any standard 24 volt DC power supply can be used, such as your existing PLC power supply.
  • A 820 ohm, 5%, 1/2 watt resistor is installed in series.
  • A green LED shows input status on the power controller
  • Zero crossing activation -- low EMI, low noise to nearby electronics
  • Available for the 25 amp DMA-6V25 or 40 amp DMA-6V40
  • UL, CSA, CE
DMA pot input

Part Number

Customer to supply the 0-5k pot, resistor, and 24 VDC power supply.

DMA-6V25   up to 25 amps, 660V max, analog input activated Buy
DMA-6V40   up to 40 amps, 660V max, analog input activated Buy

(As an alternative, you could also use this combination: a 1500 ohm pot; a 270 ohm, 5%, 1/4 watt resistor; 24 vdc power supply, and a DMA-6V__ solid state contactor.)

DDA temperature curver


Part Number Line Voltage Range (VAC) Load Current Range (A RMS) Max Voltage Drop at 20mA
DC activated
DMA-6V25 24-660 .10-25 6VDC
DMA-6V40 24-660 .10-40 6VDC
Off-State dv/dt 1000 v/µs
Isolation 4000 volts
I²T fuse 50A or less, for example: Bussman FWP50A14F, FWC32A10F, FWC20A10F. Ferraz Shawmut B093910, M330015, K330013
Example of control 0% = heater or load is "off"
50% = heater "on" 250 mseconds, "off" 250 msec, "on" 250 msec...
75% = "on" 375 msec, "off" 125msec, "on" 375 msec....
85% = "on" 425 msec, "off" 75msec, "on" 425 msec....
100% = heater "on"

Since the contactor is switching at the zero crossing mark of a sinewave, there is no electrical noise that might interfere with nearby electronics. Also, since the calculated ON or OFF time period is measured in half sine waves, the contactor will automatically adjust the total cycle time in order to maintain the best ratio of ON/OFF to match your control input.
Turn-on time <8.3 msec at 60hz
Turn-off time <8.3 msec at 60hz
Terminals Will accept #24-#10 AWG wire. Torque: 7-9 inch lbs.
DDA size