PILZ P1MS 17474 / 230V/1A/1R THERMISTOR PROTECTION RELAY 479940
- BRAND: PILZ
- MODEL:Â P1MS 17474
- 230V, 1A, 1R
- THERMISTOR PROTECTION RELAY
- 479940
The Pilz P1MS 17474 is a compact and reliable thermistor motor protection relay designed to protect three-phase motors from overheating and damage caused by overload, phase failure, and asymmetric phase currents. It operates by monitoring the resistance of PTC (Positive Temperature Coefficient) thermistor sensors embedded directly in the motor’s windings, providing a highly accurate and direct temperature-based protection.
This specific model, 230V1A1R, is configured for a control supply voltage of 230V AC and features one relay output (1A1R).
Key Features
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Direct Temperature Monitoring:Â Uses PTC thermistors for precise and reliable protection against motor overheating, independent of the motor’s current.
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Comprehensive Motor Protection:Â Safeguards motors against:
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Overheating (Primary function via PTCs)
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Phase Imbalance (Asymmetry)
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Phase Loss (Phase Failure)
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Compact Design:Â The slim housing (22.5mm wide) saves valuable space in the control cabinet.
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Easy Installation & Wiring:Â Clear marking and a plug-in terminal block simplify installation and maintenance.
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High Noise Immunity:Â Designed for reliable operation in industrially harsh environments with electrical interference.
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Manual or Automatic Reset:Â User-selectable reset mode via a DIP switch.
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LED Status Indication:Â Provides clear visual feedback on the operational status (Ready) and fault condition (Trip).
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer / Model | Pilz P1MS 17474 |
| Article Number | 479940 |
| Supply Voltage | 230 V AC (50/60 Hz) |
| Output Relays | 1 Changeover (CO) Relay (1A1R) |
| Max. Switching Capacity | 6 A / 250 V AC |
| Sensor Input | 2 PTC Thermistor sensors (typically in series) |
| Trip Threshold | Typically 3.0 – 4.5 kΩ (standard for PTC sensors) |
| Reset Mode | Manual (via button) or Automatic (selectable) |
| Protection Functions | Overtemperature (PTC), Phase Imbalance, Phase Loss |
| Mounting | Standard 35 mm DIN Rail (EN 60715) |
| Width | 22.5 mm |
| Ambient Temperature | -20 °C to +60 °C |
| Standards & Approvals | CE, cULus Listed, ATEX (for specific versions) |
Function and Application
How it Works:
PTC thermistors are resistors whose resistance increases significantly at a specific temperature (the response temperature). Several of these sensors are embedded in the motor’s stator windings during manufacturing. The P1MS module continuously monitors the total resistance of the sensor circuit.
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Normal Operation:Â Sensor resistance is low. The relay is energized, allowing the motor to run (Safety Relay closed).
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Overtemperature Condition:Â If the motor overheats (due to overload, blocked rotor, insufficient cooling, etc.), the PTC sensors heat up. Once their resistance exceeds the trip threshold, the P1MS detects the fault, de-energizes its safety relay, and interrupts the motor control circuit, stopping the motor.
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Reset:Â After the motor and sensors have cooled down, the relay can be reset either automatically or manually (depending on the setting) to restart the system.
Typical Applications:
This relay is ideal for protecting critical motors in various industrial applications, including:
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Conveyor systems
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Pumps and fans
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Machine tools
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Mixers and agitators
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Packaging machinery
