Chromalox’s heater controller provides small footprint

Pittsburgh, Pa. - Chromalox reports its recently introduced MaxPac compact silicon-controlled rectifier (SCR) power controllers have a footprint approximately 30% smaller than competing systems.

By Jim Montague, news editor January 2, 2002

Pittsburgh, Pa. – Chromalox reports its recently introduced MaxPac compact silicon-controlled rectifier (SCR) power controllers have a footprint approximately 30% smaller than competing systems. The firm says this makes the controllers especially well suited for embedded OEM applications.

MaxPac includes controllers for single-phase, three-phase/two leg, and three-phase/three leg configurations. They provide power control output of 120-575 V ac at 100-1200 A and are suitable for high-power resistive or infrared heating in industrial applications.

MaxPac controllers also feature a temperature warning and shutdown system. When an electronic temperature sensor on the heat sink registers an overheating condition, users are notified via a contact closure. If the condition worsens, the system will shut down automatically. Chromalox states this approach allows earlier corrective action.

The controller’s optional plug-in card for shorted SCR detection has an auto-configuration feature, which provides detection of shorted SCRs and the circuit legs where they’re located. Other safety features include input-to-output isolation, transient over-voltage protection and remote shutdown capability. On controllers rated up to 650 A, safety is further enhanced with grounded heat sinks.

Users can choose between on/off or proportional control, and they can also use Chromalox’s demand oriented transfer (DOT) firing. DOT firing is designed for applications where consistent heater/process temperature is critical. It switches the fewest number of cycles to provide the most precise zero crossover control. For example, at 50% output, the unit’s output alternates between three electrical cycles on and three electrical cycles off. At 51%, the output continues with three cycles on/off, and gradually integrates extra ‘on’ cycles for the additional 1%.