Modular SCR Power Controller for Custom Tailoring to the Application

The QPAC modular controller from Watlow is a modular silicon controlled rectifier (SCR) power controller with plug-in features for flexibility. Bases are rated from 150 to 1000 amperes in one-phase, three-phase, two leg and three-phase, three leg configurations.

A variety of transformers from 120 to 575VAC, along with 50/60Hz operation, enable the QPAC modular controller to operate in applications anywhere. Plug-in control cards set the QPAC's SCR firing modes: solid state contactor, burst firing (zero cross) or phase-angle models and are available with a wide variety of options. High speed fuses are included to protect the SCR modular controller from short circuit currents. 200KA short circuit current rating (SCCR) prevents arc flash.

Features & Benefits

200KA short circuit current rating (SCCR) prevents arc flash

Modular power controller offers a variety of plug-in transformers and controller cards

Available in 150 to 1000 ampere ratings for large or medium size loads

Available in solid state contactor, burst firing (zero cross) or phase-angle fired mode to meet most application requirements

Rugged design for 122°F (50°C) ambient operation can be used in industrial applications with full rating of the power controller

Semiconductor fuses and snubber protection included

Protects the SCR from voltage or current surges or spikes

Open heater or shorted SCR detector option

Performs diagnostics

UL® 508 listed and C-UL® up to 1000 amperes

Meets applications requiring agency approvals


Description Information
Mounting Back panel
Profiling No
Max Output 1000A
Output Firing Zero Cross, Phase Angle
Phase Configurations 1 or 3
Ambient Operating Range 0 to 50°C (32 to 122°F)
Agency Approvals UL®, C-UL®, SCCR
TRU-TUNE®+ Adaptive Control No
Remote Limit Reset No
Warranty (Years) 3

Related Documentation

  • User Manuals

    Cross Reference for Semiconductor Fuses and Holders for Watlow Power Controllers

    QPAC Modular SCR Power Control Service Manual

    QPAC User's Guide

  • Agency Approvals

    Agency Approvals for Watlow Controllers

    CCC Winona Exemption Letter

  • Brochures

    SCR Power Controllers

  • Training and Education

    Current Limit function - Oscilloscope Video

    Phase Angle function - Oscilloscope Video

    Soft Start Function - Oscilloscope Video

    Variable Time Base Zero Cross Function - Oscilloscope Video

  • Catalogs

    Controller Catalog (Section) - Power Switching Devices

    Sensor & Controller Catalog

  • Specification Sheets

    Combined Branch Protection and Semiconductor Fusing

    DIN-RAIL Semiconductor Fusing

    QPAC SERIES Power Controller

  • White Papers

    Calibration for DIN-A-MITE Bias and Gain

    SCCR - Short Circuit Current Rating for Watlow Power Controls

Request A Quote Configure Your Controller Get Application Assistance

Quality Certificates

ISO 90012008 Certificate - Controllers Winona