Viconics SCR Power Controllers

Viconics SCR Power Controller

SCR power controllers are designed for an accurate and cost effective way to modulate electric heat. Useful for electric reheat and supplemental electric duct heaters. Viconics’ R820 SCR power controller has been designed for safe and reliable control of electric heat loads. As a result, this broad line of products is used by most major North American duct heater manufacturers.


  • High efficiency, black anodized heat sink improves heat dissipation
  • Zero-cross firing minimizes interference to other loads
  • Multi-input signals (0-10Vdc; 4-20mAdc; 0-135 ohm)
  • LED to indicate proper operation
  • Quick connect, slave terminal to connect to R810 power switches

What is an SCR controller?
If you really want to impress your buddies, give them an explanation of what the SCR initials mean:

The Silicon Controlled Rectifier

The basic purpose of the SCR is to function as a switch that can turn on or off small or large amounts of power. It performs this function with no moving parts that wear out and no points that require replacing. There can be a tremendous power gain in the SCR; in some units a very small triggering current is able to switch several hundred amperes without exceeding its rated abilities. The SCR can often replace much slower and larger mechanical switches. The SCR is an extremely fast switch. It is difficult to cycle a mechanical switch several hundred times a minute; yet, some SCRs can be switched 25,000 times a second. It takes just microseconds (millionths of a second) to turn on or off these units. Varying the time that a switch is on as compared to the time that it is off regulates the amount of power flowing through the switch. Since most devices can operate on pulses of power, the SCR can be used readily in control applications. Motor-speed controllers, inverters, remote switching units, circuit overload protectors, latching relays, and computer logic circuits all use the SCR.

R820-211 240 10 1
R820-213 240 10 3
R820-321 347 25 1
R820-323 347 25 3
R820-421 480 25 1
R820-423 480 25 3
R820-621 600 25 1
R820-623 600 45 3
R820-341 347 45 1
R820-343 347 45 3
R820-441 480 45 1
R820-443 480 45 3
R820-641 600 45 1
R820-643 600 45 3
R820-471 480 75** 1
R820-671 600 75** 1
NOTE: Only 2 legs of the circuit are controlled on 3 phase models
** 75 amp models are only available in single phase.

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