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QPAC Modular Silicon Controlled Rectifier Power Controller


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The QPAC 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.

A variety of transformers from 120 to 575VAC, along with 50/60Hz operation, enable the QPAC 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 from short circuit currents. 200KA short circuit current rating (SCCR) prevents arc flash.



Features and Benefits · Specifications · Applications Sketch · Accessories

Features and 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
  • Handles large or small loads
Available in solid state contactor, burst firing (zero cross) or phase-angle fired mode
  • Meets most application requirements
Rugged design for 122ºF (50ºC) 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



Specifications

Modular controller base with plug-in card and transformer
  • Plug-in control cards:
    Solid state contactor, ac or dc input
    Burst-fire controller, fixed or variable time base
    Phase-angle fire control
    Phase-angle control with soft start and current limiting
  • Plug-in transformers (50/60Hz)
  • 120, 208, 240, 380, 415, 480, 575VAC operation
Power bases
  • 1-phase (Q01), 1 pair of SCRs
  • 3-phase (Q32), 2 leg control, 2 pair SCRs Resistive load only, burst firing only
  • 3-phase (Q33), 3 pair hybrid SCRs/diodes Recommended for phase-angle only with balanced load
Agency Approvals
  • UL® 508 and C-UL® listed, 150 to 300A all configurations, File #E73741
  • UL® 508 and C-UL® listed, 400 to 1,000A on Q01 and Q32, up to 480VAC
Control Card Input Options
Solid state contactor, ac input (CA option)
  • 120VAC @ 30mA min.
  • AC signal input sources (i.e., triacs or mechanical relay outputs with noise suppression) require customer supplied resistors across the power controller ac command signal input terminals to prevent false firing
  • 24VAC input, 200Ω/10 W typical;
  • 120VAC input, 1kΩ/25 W typical;
  • 240VAC input, two 1kΩ/25 W in series typical
Solid state contactor, dc input (CD option)
  • On, 4-10VDC; off, 0.5VDC
  • Built-in noise reduction network
Burst-firing controller, fixed time base (BF option)
  • Process input factory set @ 4-20mA DC
  • Input impedance 250Ω (clip resistor for 5kΩ impedance voltage input), or manual control input
  • Time base 4 seconds (clip resistor for 1 sec)
Burst-firing controller, variable time base (BV option)
  • Process input factory set @ 4-20mA dc
  • Input impedance 250Ω (clip resistor for 5kΩ impedance voltage input), or manual control input. Requires an accessory bias and gain card to calibrate for 0-5VDC input.
Phase-angle control (AF option)
  • Process input factory set @ 4-20mA dc
  • Input impedance 250Ω (clip resistor for 5kΩ impedance voltage input), or manual control input
  • Soft start approximately 6 seconds upon power-up, 1 second upon set point change
Phase-angle control with current limit (AL option )
  • Process input factory set @ 4-20mA dc
  • Input impedance 250Ω (clip resistor for 5kΩ impedance voltage input), or manual control input
  • Soft start approximately 10 seconds upon power-up, 1 to 2 seconds upon set point change
  • Current transformer included
Open Heater/Shorted SCR Detector
  • Zero cross/burst fire models only
  • Triac output
  • 24 to 240VAC, 300mA @ 77ºF (25ºC), 125mA @ 176ºF (80ºC)
  • Energizes on alarm
  • Holding current 200µA min.
  • Latching current 5mA typical
Outputs
  • 120 through 575VAC
  • 1, 2 or 3 leg
  • 150 to 1000A per leg
  • SCCR, 200KA with original equipment specified semiconductor fusing
  • Fan cooled
Line Voltage / Power
  • 50/60Hz ac line frequency, Q32 and Q33 models are 50/60Hz calibration dependent
  • Voltage: ±10%, 120, 208, 240, 277, 380, 415, 480, 575VAC
Line Voltage Compensation
  • 10% Δ in line, 2% Δ in load in the 30 to 70% power region (AF, AL and BV)
Power Dissipation (Watts)
  • 1.5 W/A per controlled leg
Isolation
  • Command signal to load 1250VAC min.
Linearity
  • 2%, 30 to 70% power region (All units except CA and CD)
Off-State Leakage Current
  • 20mA @ 480VAC
SCR Protection
  • Semiconductor fuses provided dv/dt 200V/µsec min.
  • MOV (MOV comes only on Q33 (3-phase, 3 leg).) and RC snubber network standard
  • (Q32) 3rd leg fuse kit may be used, but not required, with 3-phase, 2 leg models
Mounting
  • Heat sink fins must be mounted in vertical orientation
Operating Environment
  • 32 to 122ºF (0 to 50ºC)
  • 0 to 90% RH (relative humidity), non-condensing
  • 2,000 meters altitude max.
Storage Temperature
  • -40 to 185ºF (-40 to 85ºC)
Options
  • Manual control kit for process input cards (1kΩ potentiometer) #08-5362
  • 240VAC and 120VAC cooling fans



Applications Sketch

In heat treating applications, the QPAC offers modular flexibility. Different heater elements require different control firing modes: i.e., tungsten elements need phase-angle firing, while Nichrome® elements use burst (zero cross) firing.

Shipping the furnace to different countries could require different voltage sources (and thus transformers): i.e., United States 240 or 480 volt, Australia 415 volt; Europe 380 or 400 volt. By simply changing plug-in transformers, the OEM can ship anywhere in the world.


Accessories

Manual Control Kit - 08-5362
150A : 5A Current Transformer - 16-0008
200A : 5A Current Transformer - 16-0045
300A : 5A Current Transformer - 16-0073
400A : 5A Current Transformer - 0004-0286-0400
500A : 5A Current Transformer - 0004-0286-0500
600A : 5A Current Transformer - 0004-0286-0600
800A : 5A Current Transformer - 0004-0286-0800
1,000A : 5A Current Transformer - 0004-0288-1000
5A : 20mA Interstage Transformer - 16-0176



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· Case Styles

· Applications Sketch

· Wiring Example

· QPAC Output Ratings and Dimensions

· QPAC Weight Chart