Three Phase Thyristor Power Switch for
Duct Heaters – POW-3-ZC (24KW to 54KW)
Three Phase Thyristor Power Switch for Duct Heaters – POW-3-ZC (24KW to 54KW)
Libratherm offers a three-phase heater power regulator model POW-3-ZC-2L-XXA for electric power control of resistive heating loads operating on three-phase 415VAC. This regulator accepts the user-selectable DC control signal of 0-5V, 0-10V, and 4-20mA and can be easily interfaced with BMS, DDC, PID, or PLC. An external potentiometer can also be used for manual control. The On-Off duty cycle of voltage across the heaters can gradually vary proportionally to the input signal. For a preset cycle time of 4 seconds, 50% power will be delivered by keeping the heater ON for 2 seconds and OFF for 2 seconds.
The facility is also provided to protect against the regulator overheating. Under normal conditions, the built-in thermostat switch will remain closed and go open when the device or heat-sink temperature crosses around 90oC. The user can connect an external alarm relay to the interlock. Auto control through an external control signal or Manual control using a card preset is user-selectable.
These POW-3-ZC-2L-XXA models are available in a rugged powder-coated metallic enclosure with an extruded aluminum heat sink and can be easily fitted inside the panel. A high-speed cooling fan operating on 24VDC is provided within the assembly to keep the heat-sink material cool against overheating.
Key Features:
- Solid-state, field-proven, rugged and reliable design.
- Operates on 24VAC/DC
- Control signal 4-20mA/0-5V/0-10V/Potentiometer (Factory set to 0-10V)
- Three phase two leg – zero cross-over Burst fire switching control
- LED indications for Power ON, Input Command and Over temperature of the heatsink.
- Built-in thermostat for Auto-Reset Over-Temperature protection
- Built-in 24VDC operated cooling fan on Heat-Sink.
- Designed for three-phase heater load of 6KW to 25KW@ 415VAC
Applications:
- Air Heater power control in AHU duct
- Power control of Resistive heater used in Industrial Applications
| Parameters | Description |
|---|---|
| Item | Three Phase 2 Leg Control Thyristor-based heater power regulator |
| Model | POW-3-ZC-2L-XXA (As specified in the above table) |
| Control Signal Input (Linear) | 0-5V, 0-10V, 4-20mA or using an external 10K potentiometer. (Factory set to 0-10V) |
| Control Technique | Zero Cross Over Burst Firing control |
| Aux. Supply Voltage | 24VAC/DC +/-10% @ max 10 Watt. (including supply to the FAN) |
| Heater Supply Voltage | 380 to 440VAC three phase @ 50/60Hz |
| Max. Load Current | 35A to 75A @ 380 to 440VAC (As per the model specified in the above table) |
| Auto/Manual Control | The on-card jumper is selectable. The heater output voltage is scalable using the on-card single-turn preset marked SCALE. |
| Over Temperature Protection | A thermostat of 90oC is mounted on a heatsink. (NC type). |
| Alarm Output | 24VAC/DC supply point is available at the terminal in series with the NC contact of the Thermostat. |
| Mounting | Base plate mounting using four screws. |
| Connections | 5A Terminal PCB connectors for Auxiliary Supply and control signal, heavy-duty Terminal PCB connectors for Heater Supply and Heater load. (For the models up to POW-3-ZC-2L-45A or 30KW/45A. For the higher current rating models, suitable sizes of Aluminum bus bars are provided for heater supply and heater load connections. |
| Cooling | Forced Air cooling using a 3-inch FAN, operated on 24VDC @ 3Watt |
| Dimensions | As given in the Ordering Information table. |
| CE Certification | Low Voltage Directives - 2014/35/EU and EMC Directives – 2014/30/EU |
| Model | Description | Size (W x H x D) mm | Part No. |
|---|---|---|---|
| POW-3-ZC-2L-35A | Three-phase heater power regulator for max. 24KW @ (380-440) VAC | 130 x 225 x 120 | 2757 |
| POW-3-ZC-2L-40A | Three-phase heater power regulator for max. 27KW @ (380-440) VAC | 130 x 235 x 120 | 2758 |
| POW-3-ZC-2L-45A | Three-phase heater power regulator for max. 30KW @ (380-440) VAC | 130 x 245 x 120 | 2759 |
| POW-3-ZC-2L-50A | Three-phase heater power regulator for max. 36KW @ (380-440) VAC | 150 x 240 x 160 | 2760 |
| POW-3-ZC-2L-60A | Three-phase heater power regulator for max. 42KW @ (380-440) VAC | 150 x 240 x 160 | 2761 |
| POW-3-ZC-2L-75A | Three-phase heater power regulator for max. 54KW @ (380-440) VAC | 150 x 240 x 160 | 2762 |
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