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POWER SERIES™ Solid State power Controllers

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Watlow has manufactured solid state power controllers for over forty years. Watlow's POWER SERIES™ is a microprocessor-based product that features application flexibility unmatched by any other silicon controlled rectifier (SCR) power controller on the market today.

Watlow's POWER SERIES controllers include single and three-phase models from 65 to 250 amperes. Field configurable phase-angle or zero-cross firing improves application flexibility on site where needed.

50/60Hz independent operation allows utilization almost everywhere in the world without special calibration considerations. Serial communication via Modbus® RTU allows setup and monitoring of load status from a computer station or control room.

On-board semiconductor fusing improves reliability by protecting the SCRs from heater short circuits. Plus, on-board heater bakeout and control diagnostics can help eliminate initial start up problems. All these benefits are in a touch-safe package that can be quickly and easily mounted in a control cabinet.

Watlow’s POWER SERIES controllers are UL® listed and C-UL® recognized, ensuring that they meet world safety and operational standards.

Features and Benefits · Specifications · Power Series Features

Features and Benefits

200KA short circuit current rating (SCCR)
  • Prevents arc flash
Microprocessor-based technology
  • Extremely versatile and field configurable
Snap-fit on a pre-mounted plate
  • Simplifies installation
Models 65 through 250 amperes rating
  • Handles a wide range of loads
Adjustable soft start
  • Provides application flexibility
Heater and control diagnostics capability
  • Monitors actual heater and controller performance
Electrically touch-safe package
  • Enhances safety for installer and users
Serial communications with Modbus® RTU protocol
  • Provides computer control and/or monitoring
Multizone capability
  • Increases application flexibility and reduces panel space


Power Bases
  • Single-phase, (2 SCRs)
  • 3-phase, 2-leg control, (4 SCRs)
    Resistive load only, zero-cross firing only
  • 3-phase, 3-leg control, (6 SCRs)
  • 3-phase, 3-leg control, (6 SCRs) for 4-wire wye loads
  • Multizone, two and three single-phase zones
Output Control Options
  • Zero-cross control, fixed time base
    • Time base one or four seconds with digital programmer
  • Zero-cross control, variable time base
  • Phase-angle control and phase-angle control with current limit (not for 3-phase, 2-leg models)
    • Soft start factory default four seconds upon power-up, and adjustable from 0.0 to 120 seconds
    • Soft start upon input signal change, output rate of change adjustable to limit max. rate of change from 0.1 to 100% per 0.1 second. Factory default 10%
  • Current transformer included when required
  • Line voltage compensated (variable time base and phase angle controllers only)
  • Standby or non-operational mode
Output Voltage and Current Rating
  • 24 to 120VAC (+10%, -15%)
  • 200 to 480VAC (+10%, -15%)
  • 200 to 600VAC (+10%, -15%)
  • 65 through 250A per pole, model dependent; see output amperage chart and rating curves
  • Min. load 1A rms ac
  • Max. leakage current 5mA
  • 200KA SCCR, Type 2 approved with the recommended fusing; see user manual
  • Single alarm relay
  • Latching or non-latching
  • Separate high and low values
  • Alarm silencing (inhibit) on power up for alarm
  • Alarm indication LEDs, shorted SCR, open heater, fuse
  • Electromechanical relay, Form C contact, software configurable
    • Min. load current 10mA @ 5VDC
    • Rated resistive loads: 3A @ 250VAC or 30VDC max., inductive load rating 1.5A with a power factor ≥ 0.4 without contact suppression
Heater Bakeout
  • For single-phase (phase to neutral) and 3-phase 6 SCR models only (not for 3-phase, 2-leg models)
  • Soft start with over current trip, runs until programmed bakeout time expires, then goes burst or phase-angle firing. Factory default of 24 hours
  • Adjustable 0 - 9999 minutes with over current trip
  • Internal current transformer included
Command Signal Input
  • Field selectable linear voltage and current of low and high points within 0-20mA and 0-10VDC
  • Manual control input through front panel
  • Factory default 4-20mA input
  • Voltage input impedance 11kΩ nominal
  • Current input impedance 100Ω nominal
  • On-board digital programmer/display and optional serial communications
  • Field selectable and scalable within 0-20mA, 800Ω max. or 0-10VDC, load, 1KΩ min. load. The default is 4-20mA
  • Resolution:
    mA ranges = ±5µA
    VDC = ranges 2.5mV nominal
  • Calibration accuracy:
    mA ranges = ±20µA
    VDC ranges = 10mV nominal
  • Temperature stability: 100ppm/ºC
Digital Programmer/Display and Communications Capabilities
  • Programming functions
    • Adjust input and output control type, alarms and soft start, heater bakeout and current limit prompts
  • Monitoring functions
    • Display input and output values along with actual output current
  • Data retention of digital programmer/display upon power failure via nonvolatile memory
Serial Communications
  • RS-232 for single drop control
  • EIA-485 for single or multidrop control
    • 32 units max. can be connected. With additional 485 repeater hardware, up to 247 units may be connected
  • Isolated
  • Modbus® RTU protocol
  • 1200, 2400, 4800, 9600, 19200 baud rates
Controller Power Supply
  • Universal line voltage input range 100 to 240VAC (+10%, -15%) at 55VA max.
  • 50/60Hz ± 5% line frequency independent
  • Controller line voltage for electronic power supply can be run on separate line voltage
Natural Convection and Fan Cooled Models
  • Cabinet venting may be required
Power Dissipation (Watts)
  • Approximately 1.25 watts/amperes per controlled leg
  • Command signal to load and line/load to ground 2200VAC min.
  • On-board semiconductor fuses provide SCR protection
  • Mounts on a removable subplate
  • Heat sink fins must be mounted in vertical orientation
High Current Terminals
  • Touch safe
  • 3/8 in. (10 mm) Allen head compression terminals will accept #6 AWG to 350 MCM wire. Allen wrench adapter (included) for 3/8 in. (10 mm) socket, 6 point only
  • Torque to 180 in.-lb (20.3 Nm)
  • Wire strip to 1 1/8 in. (30 mm)
  • Requires 194ºF (90ºC) wire insulation rating on line and load terminals
Controller Terminals
  • Touch safe
  • 1/8 in. (2.5 mm) blade screwdriver, accepts 12-22 AWG or 2 No. 22-18 AWG wires
  • Torque to 8 in.-lb (0.9 Nm)
  • Wire strip to 0.24 in. (6 mm)
Operating Environment
  • 122ºF (50ºC) base rating
  • 32 to 140ºF (0 to 60ºC) fan cooled
  • 32 to 149ºF (0 to 65ºC) natural convection cooled
  • 0 to 90% RH (relative humidity), non-condensing
  • Meets EN50178, Pollution degree 3
Storage Temperature
  • -40 to 185ºF (-40 to 85ºC)
Shipping Weight
  • 23 lb (10.3 kg)
Agency Approvals
  • UL® 508 listed, File #E73741, Vol. 3, Sec. 2
  • C-UL® listed to C22.2 NO. 14
  • CE 2004/08/EC (EN61326-1), Class A with filter, CE 2006/95/EC (EN50178)

Power Series Features

Removable Mounting Plate
POWER SERIES snaps on a pre-mounted, removable subplate.

Terminal Cover
Electrically touch-safe package.

Fuse Cover
Slides up and down for fuse maintenance and covers the high voltage components.

Digital Programmer/Display
For controller configuration, setup and monitoring features.

Ground Lug
Built in, designed for easy ground connections.

I/O Port
Input, retransmit output, communications and alarms.

On-Board Fan
Is integrated into the package on forced air cooled models to eliminate separate power connection for fan.

Allen Wrench
Used to torque terminals one to six and ground lug.

Single-Phase Configuration
This configuration can be purchased with any or all the features available on the POWER SERIES, based on customer preference. It is intended for resistive heaters, but can also be used on transformer connected loads in the phase-angle firing mode.

Three-Phase, Two-Leg Configuration
This configuration is intended for zero-cross firing only into a stable resistive heater. Typically, a three-phase delta or ungrounded wye connected heater is used and only two of the three VAC line phases are switched. The third phase is a direct connection through a bussbar on board the POWER SERIES. Heater current monitoring and kVA options are available via the heater diagnostics option.

Three-Phase, Three-Leg Configuration
All POWER SERIES options are available with this configuration. It works well with phase angle firing into a three-phase, three-wire wye or delta connected heater. In this configuration, the more common applications are transformer connected loads with heaters requiring a soft start and/or current limiting.

The three-phase, four-wire configuration is intended for zero cross firing into a three-phase grounded wye/star heater (This is a separate hardware option, model number dependent.)

Single-Phase, Multizone Configuration
This configuration is available in two and three single-phase zones and all the features of a single-phase unit are available. (Note that there is only one alarm relay and all zones in the controller must use the same control method.)

Heater Diagnostics
Heater diagnostics may include some or all of the features that require heater current monitoring, depending on the model selected. Heater current monitoring is only available with heater diagnostics installed on the controller. The features dependent on heater current monitoring are heater bakeout, current limiting, heater kVA monitoring, retransmit and heater monitoring alarms such as open heater, heater out of tolerance, load balance and shorted SCR detection/error. Heater diagnostics must also be installed if you need phase angle control with current limit.


· Package Style C Dimensions

· Mounting Plate Dimensions