Thayer Scale manufactures industrial control panels certified for the U.S. and Canadian markets through UL’s Panel Shop Program.
When existing motor control centers (MCCs) are full or cannot accommodate additional drives, Thayer Scale offers packaged Power Control Assemblies (PCAs).
These self-contained PCAs convert standard AC utility power into adjustable AC or DC output for precise feeder and conveying control.
- Permanent magnet or shunt wound DC motors
- Inverter-duty AC motors
- Electromagnetic drives used with vibratory tray feeders
Every Thayer Scale PCA
includes:
- Code-compliant external disconnect (as required by input utility)
- Branch circuit protection (fusing)
- Interlocking logic to support a variety of operating modes
- Terminal strip for user’s input utility, and input and output wiring
- Adjustable speed drive (VFD, SCR, voltage regulator)
- Components needed to complete a basic analog drive controller package
When existing motor control centers (MCCs) are full or cannot accommodate additional drives, Thayer Scale offers packaged Power Control Assemblies (PCAs).
These self-contained PCAs convert standard AC utility power into adjustable AC or DC output for precise feeder and conveying control.
Customization Options
Chassis mounting construction that can be installed within a panel or enclosed for field mounting in any location
Local or remote operator station
Ethernet IP device level interface (VFD only)
Need Help Selecting the Right Power Control Assembly?
Thayer Scale can help specify the proper Power Control Assembly for your application.
Available PCA Configurations
| Feature | AC Variable Frequency Drive (VFD) Systems | SCR Packaged Drive Systems | PCA-VIB Controllers |
| Controlled Device | Inverter-duty AC motors | Permanent magnet and shunt wound DC motors | Electromagnetic vibratory tray feeders |
| Output Type | Adjustable frequency AC output | Adjustable DC output | Adjustable regulated AC voltage |
| Typical Applications | Weigh belt feeders, screw feeders, loss-in-weight feeders, volumetric feeders | Existing feeder retrofits, legacy DC drive applications, precision speed control | Electromagnetic vibratory feeders and tray feeders |
| Speed Control Method | Variable frequency drive (VFD) | SCR drive controller | Voltage regulator |
| Low-Speed Performance | Sensorless vector control | Excellent low-speed torque characteristics | Precise vibration amplitude control |
| Operator Interface | Local or remote operator station available | Local or remote operator station available | Manual potentiometer or external control signal |
| Communications | Ethernet/IP available | N/A | N/A |
| Installation Options | Chassis mounted or enclosed field-mounted package | Chassis mounted or enclosed field-mounted package | Enclosed package |
| Branch Circuit Protection | ✓ | ✓ | ✓ |
| External Disconnect | ✓ | ✓ | ✓ |
| Interlocking Logic | ✓ | ✓ | ✓ |
| User Terminal Strip | ✓ | ✓ | ✓ |
| UL Certification | UL Panel Shop Program | UL Panel Shop Program | UL Panel Shop Program |
AC Variable Frequency Drives (VFDs)
Designed to provide precise speed control for feeders utilizing inverter-duty AC motors.
Features
- Adjustable frequency output
- Sensorless vector control for improved low-speed torque
- Complete enclosure with disconnect and branch protection
- Easy installation and configuration
- Easy integration with feeder controls
- Compatible with customer-preferred drive manufacturers when required
- Available with Allen-Bradley, SEW, or other customer-specified drives that meet Thayer standards
Typical Applications
- Weigh Belt Feeders
- Loss-in-Weight Feeders
SCR Packaged Drive Systems
Designed to provide adjustable DC output for feeders utilizing permanent magnet or shunt wound DC motors.
Ideal For
- Existing feeder retrofits
- Applications requiring precise speed control
- Legacy installations utilizing DC drive technology
PCA-VIB Controllers
Designed specifically for electromagnetic vibratory tray feeders.
Available Models
- PCA-VIB-120: 0–110 VAC
- PCA-VIB-240: 0–220 VAC
Features
- Manual speed potentiometer or external speed signal control
- Supports electromagnetic vibrating tray motors up to 15 amps
- Simple analog drive package for vibratory feeder applications
Detailed Technical Specifications
Primary Use
Variable speed control for AC motors used in weigh feeders, screw feeders, and volumetric feeders
Motor / Drive Type
Inverter-duty AC induction motors
Input Power
100-120V, 200-240V, or 380-480V depending on drive selected
Output Type
Adjustable frequency AC output
Power Range
0.37-11 kW (0.5-15 HP) depending selected drive and application requirements
Output Frequency
0-400 Hz
Output Current
Application dependent
Control Method
Integral keypad, local potentiometer, configurable I/O, analog signals
Remote Speed Signal
±10V, 0-10V, 4-20 mA
Operator Controls
Integral keypad with display, LED indicators, local potentiometer
Communications
Ethernet/IP and other industrial communication protocols
Enclosure Options
IP20/NEMA 1, IP55/NEMA 12, IP66/NEMA 4X depending on drive selected
Included Components
Depends on selected drive package
Environmental Ratings
Depends on enclosure and drive selected
Certifications
UL Panel Shop Program
Notes
Allen Bradley Power Flex 40©, SEW Movitrac© LTE-B, or customer-specified drives meeting Thayer standards
Primary Use
Variable speed control for permanent magnet and shunt wound DC motors
Motor / Drive Type
Permanent magnet or shunt wound DC motors
Input Power
115 VAC or 230 VAC, single phase
Output Type
Adjustable DC voltage output
Power Range
PCA-115: 1/4-1 HP; PCA-230: 1/2-2 HP
Output Frequency
N/A
Output Current
Application dependent
Control Method
Manual speed potentiometer or remote current signal
Remote Speed Signal
1-5 mA or 4-20 mA
Operator Controls
Hand/Remote, hand speed adjust, start/stop
Communications
N/A
Enclosure Options
NEMA 4 or 4X wall mount enclosure or open chassis
Included Components
SCR controller, locking disconnect switch, motor starter, related components
Environmental Ratings
Depends on enclosure and drive selected
Certifications
UL Panel Shop Program
Notes
Consult factory for higher input voltages
Primary Use
Control of electromagnetic vibratory tray feeders
Motor / Drive Type
Electromagnetic vibrating tray motors
Input Power
120 VAC or 240 VAC depending on model
Output Type
Adjustable regulated AC voltage output
Power Range
PCA-VIB-120: 2500 W; PCA-VIB-240: 5000 W
Output Frequency
N/A
Output Current
0.2-15 amps
Control Method
Manual speed potentiometer or external speed signal
Remote Speed Signal
Programmable current or voltage signal
Operator Controls
Hand-Off-Remote, hand speed adjust, start/stop, emergency stop
Communications
N/A
Enclosure Options
Open chassis or enclosed style
Included Components
Locking disconnect, protective fusing, controller, motor starter
Environmental Ratings
0-45°C, 5-95% non-condensing, up to 1000 m elevation
Certifications
UL Panel Shop Program
Notes
For conventional electromagnetic vibratory tray motors with full-wave rectification