Three Phase SCR Controllers

Three Phase, Zero Cross:

The term Zero-Cross (synchronous operation of SCR's) is derived from the fact that the SCR's are turned on only when the instantaneous value of the sinusoidal wave is zero. In Zero-Cross operation, power is applied for a number of continuous half-cycles and then removed for a number of half-cycles to achieve the desired load power in the same manner as power would be controlled with a mechanical switching device. The frequency of the on-off cycles can be extremely fast because there is no limit to the number of switching operations the SCR can perform.

3 Phase, Phase Angle:

In phase-angle control, each SCR of the back-to-back pair is turned on for a variable portion of the half-cycle that it conducts. Power is regulated by advancing or delaying the point at which the SCR is turned on within each half cycle. Light dimmers are an example of Phase-Angle control.

Model	Phases	Firing Mode	Output	Current Low	Current High	Highlights
3020	Three Phase	Zero Cross	AC	10	70	Powered off of the 4/20mA loop, so no control transformer is required.
3021A	Three Phase	Zero Cross	AC	10	70	Accepts most commands.
3021B	Three Phase	Zero Cross	AC	10	70	Accepts most commands. Sync-guard smoothes out line current draw when multiple controllers are in use.
3027	Three Phase	Zero Cross	AC	85	750	Accepts most commands. Features include: Sync-guard, Trans-guard and on-board line fusing for most frame sizes.
3037	Three Phase	Zero Cross	AC	85	750	Accepts most commands. Features include: Sync-guard, Trans-guard, shorted SCR detection and on-board line fusing for most frame sizes.
3337	Three Phase	Zero Cross	AC	200	750	Accepts most commands. Features include: Sync-guard, Trans-guard, shorted SCR detection and on-board line fusing for most frame sizes.
3629C	Three Phase	Phase Angle	AC	50	1000	Higher current ratings than our solid state relay models. Features include: current limiting, over-current trip, shorted SCR detection.
3869	Three Phase	Phase Angle	DC	300	400	Accepts most commands. High current, three phase DC output.
Compact FUSION Three Phase	Three Phase	Phase Angle, Zero Cross, Burst	AC	10	160	Can be ordered in either 2 or 3 leg control with 2 leg being limited to zero cross firing. Output is controlled linearly with respect to command signal and can be set to the average or RMS value of the voltage or current, as well as true instantaneous power or external feedback.
FUSION Three Phase AC	Three Phase	Phase Angle, Zero Cross, Burst	AC	50	1200	The FUSION three phase AC power controller is a phase angle or zero cross fired controller which linearly controls, with respect to the setpoint, the AC voltage, current, or true power applied to a three phase electrical load. The 3 phase controller can be ordered in either 2 or 3 leg control with 2 leg being limited to zero cross firing. Control is achieved for 3 leg by three pairs of inverse parallel SCRs or in 2 leg by 2 pairs of inverse parallel SCRs.
FUSION Three Phase DC	Three Phase	Phase Angle, Zero Cross, Burst	DC	60	1400	The FUSION three phase DC power controller is a phase angle fired controller which linearly controls, with respect to the setpoint, the DC voltage, current, or true power applied to an electrical load. Control is achieved by means of a six SCR bridge with freewheeling diode.

Learn more about firing modes here.

Learn more about load connections here.