Analog frequency inverter VFD/SCR

single-phasevector controlwith analog interface

Overview
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 self-contained Power Control Assemblies (PCAs) that convert standard AC utility power into adjustable AC or DC output for precise feeder and conveying control.

Key drive types / supported devices

• 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 input utility, and input and output wiring
• Adjustable speed drive (VFD, SCR, voltage regulator)
• Components needed to complete a basic analog drive controller package

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)

Common Applications

• Weigh belt feeders
• Screw feeders
• Loss-in-weight feeders
• Volumetric feeders
• Electromagnetic vibratory tray feeders (with PCA-VIB controllers)

Available PCA Configurations

• AC Variable Frequency Drive (VFD) Systems: Controlled device — inverter-duty AC motors; Output type — adjustable frequency AC output; Typical applications — weigh belt feeders, screw feeders, loss-in-weight feeders, volumetric feeders; Speed control method — variable frequency drive (VFD); Low-speed performance — sensorless vector control; Operator interface — local or remote operator station available; Communications — Ethernet/IP available; Installation options — chassis mounted or enclosed field-mounted package; UL certification — UL Panel Shop Program.
• SCR Packaged Drive Systems: Controlled device — permanent magnet and shunt wound DC motors; Output type — adjustable DC output; Typical applications — existing feeder retrofits, legacy DC drive applications, precision speed control; Speed control method — SCR drive controller; Low-speed performance — excellent low-speed torque characteristics; Operator interface — local or remote operator station available; Communications — N/A; Installation options — chassis mounted or enclosed field-mounted package; UL certification — UL Panel Shop Program.
• PCA-VIB Controllers: Controlled device — electromagnetic vibratory tray feeders; Output type — adjustable regulated AC voltage; Typical applications — electromagnetic vibratory feeders and tray feeders; Speed control method — voltage regulator; Low-speed performance — precise vibration amplitude control; Operator interface — manual potentiometer or external control signal; Communications — N/A; Installation options — enclosed package (or open chassis where specified); UL certification — UL Panel Shop Program.

Available Models (examples)

• PCA-VIB-120: 0–110 VAC
• PCA-VIB-240: 0–220 VAC
• PCA-115 (SCR): 1/4–1 HP (typical)
• PCA-230 (SCR): 1/2–2 HP (typical)

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

Detailed Technical Specifications (selected)

• VFD Systems: 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 on selected drive and application. 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 protocols. Enclosure options — IP20/NEMA 1, IP55/NEMA 12, IP66/NEMA 4X depending on drive selected. Certifications — UL Panel Shop Program.
• SCR / DC Output PCA: 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 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. Enclosure options — NEMA 4 or 4X wall mount enclosure or open chassis. Included components — SCR controller, locking disconnect switch, motor starter, related components. Certifications — UL Panel Shop Program. Notes — consult factory for higher input voltages.
• PCA-VIB Controllers: 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 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. 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.

Technical specifications (summary)

• Primary uses: Variable speed control for feeders (weigh belt, screw, loss-in-weight, volumetric) and vibratory tray feeders
• Drive types supported: VFD (inverter-duty AC), SCR (DC), Voltage regulator (vibratory)
• Input power ranges: VFD — 100–120V, 200–240V, 380–480V (depending on drive); SCR — 115VAC or 230VAC single phase; PCA-VIB — 120VAC or 240VAC
• Output types: Adjustable frequency AC (VFD), Adjustable DC voltage (SCR), Adjustable regulated AC voltage (PCA-VIB)
• Power range examples: VFD — 0.37–11 kW (0.5–15 HP); PCA-115/230 — 1/4–2 HP ranges; PCA-VIB — 2500 W / 5000 W
• Remote speed signals supported: ±10V, 0–10V, 4–20mA, 1–5mA (varies by configuration)
• Control methods: Integral keypad, local potentiometer, configurable I/O, analog signals, manual potentiometer, Hand/Remote
• Communications: Ethernet/IP available for VFD systems; other industrial protocols as required
• Enclosure options: Chassis mounted, enclosed field-mounted packages, NEMA 4 / 4X, IP20/NEMA1, IP55/NEMA12, IP66/NEMA4X (drive-dependent)
• Included components: External disconnect, branch circuit protection (fusing), interlocking logic, terminal strip, drive controller, motor starter, protective fusing
• Environmental: Typical operating 0–45°C, 5–95% non-condensing (PCA-VIB example), altitude up to ~1000 m (drive dependent)
• Certifications: UL Panel Shop Program