The C1Z is a proportional, zero voltage switched power controller capable of delivering 1-98% of the applied line voltage to the directly connected electric heaters. This is accomplished by varying the percentage of AC voltage cycles conducted by an SSR (15 and 25 Amp versions) . 40 and 60 AMP packages using SCR modules. 4-20mA, pulsed DC and 120VAC input signal options. The CZ series will not control transformers or motors.

CZ Series SSR Power Controllers (15 and 25 Amp):
The CZ series controllers are available in three configurations.
C1Z - single phase control
C2Z - three phase two legs controlled, comprised of (1) C1Z and (1) CZ slave.
C3Z - three phase three legs controlled, comprised of (1) C1Z and (2) CZ slaves.
Unit of Measure



  • UL 508 listed
  • Compact and light weight
  • 100 % solid state circuitry
  • Over-rated SCR power modules
  • Over-sized heat sink
  • Full power ratings up to 50 ºC (122 ºF) ambient temperature
  • Optically isolated 4-20 mA input standard
  • Versatile “building block” custom configurations
  • Electrically isolated chassis and heat sinks to 600 Amps
  • Gold alodined chassis and heat sink
  • MOV protection on all power SCR's
  • SanRex, SemiKron, International Rectifier and Fairchild semiconductors
  • Double sided FR4 VO-94 rated glass epoxy PCB's
  • Theory of Operation


    Zero voltage switching controls proportionally turn on and off each full cycle of the power line. By varying the number of AC power line cycles, the SCR provides power to the heaters. With a variable time base, the optimum number of cycles turned on/off is achieved. This method produces less RFI line noise than phase angle fired SCRs. Power factor is 100%, while harmonic distortion is limited. Chart below, left and center shows 25% power output using variable time based zero voltage switching.

    Avatar Instruments variable time base SCR firing. Note how half cycles can be turned on and off providing 0.08 second resolution. The chart on the right shows 50% output. 
    The C1Z takes a 4-20 mA input signal from a front-end controller and varies the average voltage applied to the electric heaters. At 4 mA input, the C1Z will start applying short duration voltage pulses to the heaters, at 12 mA the pulse duty cycle will be approximately 50%, providing approximately 50% of the average line voltage to the heaters, and at 20 mA, 98% of the line voltage will be applied to the heaters. The C1Z is a POWER CONTROLLER; it CANNOT create more voltage or current. There is no "tuning" or "tuning adjustments". TROUBLESHOOTING TIP: phase angle fired controllers are recommended for very fast processes and low mass heaters. Overall process control results are set by the dynamic characteristics of the heaters, transfer medium, sensor, and the tuning of the front-end controller, not the power controller.


    Voltage Designations

    N/A 480 VAC 50/60 Hz


    N/A 15 AMPS

    Output Voltage

    N/A 0 to 99% of input voltage zero voltage

    Control Signal ( CZ Zero Voltage Switched)

    N/A 4 to 20 mA at 3 volts DC per zone

    Input Impedance

    N/A 150 ohms per zone


    N/A less then 15% deviation

    Response Time

    N/A 12 mS (STD unit, non soft start)


    N/A 190 ºF (fan cooled units only)

    Power Dissipation (Watts)

    N/A 1.2 x maximum current

    Zone Designations

    N/A 2

    Method of Firing

    N/A Z-Zero Voltage Switched

    Ordering Note

    N/A add "-120" to part number.


    120 VAC Input Signal

    N/A add "-VDC" to part number.

    Manual Control

    N/A Use Avatar MAP. Isolated Potentiometer.

    Zero Voltage Switched Options

    R Options

    N/A -R120 - 120 VAC on-off command signal -R32 - 10-32 VDC on-off command signal

    3-Phase Control Options

    N/A 2-leg zero voltage switched A3Z style, add “-2Z” to part number.
    Example: 6CZ-48-70-2Z has six SCR packs, controlling three 2-leg 3-phase heater loads.

    3-leg zero voltage switched A6Z style, add “-3Z” to part number.
    Example: 6CZ-48-70-3Z has six SCR packs, controlling two 3-leg 3-phase heater loads.

    Electrical Connections

    N/A Check the Avatar serial tag and verify the correct voltage/ ampere ratings and input control signal for your application. Wiring must be performed in accordance with any and all applicable local and national codes. Use a minimum wire size of 16 AWG for a 10 amp CZ, 14 AWG for a 15 amp CZ, and a minimum of 10 AWG for a 25 amp CZ. For best results keep control signal and power wires separated.


    N/A All Avatar Instruments products carry a full three year, from date of purchase, parts and labor warranty against component failure and defects in workmanship. In the event your controller fails to perform properly, contact Avatar to obtain a return authorization number. Controllers sent to Avatar for warranty service that have no apparent defect will be treated as a standard repair and a $50.00 charge will be applied. Avatar will repair or replace any unit that failed due to defective parts or assembly. This warranty DOES NOT cover damage due to shipping, abuse, misapplication or operation beyond specified rating. Further more fuses and improperly fused SCR's are NOT COVERED by this warranty. Avatar is not responsible for any subsequent or other damage experienced in use of this device.