S1MN 24VAC/DC 2C/O Pilz

S1MN 24VAC/DC 2C/O PILZ Safety Relays

Brand：PILZ Model number：S1MN 24VAC/DC 2C/O

Country of origin: Germany Product weight：0.55kg

HS code：9032899099

Product Details：

Product Dimensions：

The relay functions by monitoring the resistance of a connected PTC sensor. When the sensor's temperature rises above a predetermined limit, its resistance increases sharply. The S1MN detects this change and de-energizes its output contacts, thereby shutting down the monitored equipment to prevent damage from overheating. The '2C/O' in the product name indicates it has two changeover contacts, which can be used as auxiliary contacts for machine control and signaling.

Product Specifications

Function: Thermistor monitoring relay (Overheat protection for motors, generators, etc.)
Supply Voltage ( $U_B$ ): $24 \text{ V AC/DC}$ (This version operates with both AC and DC supply)
Contact Type: Two auxiliary contacts ( $2 \text{ C/O}$ , Changeover contacts)
Terminal Type: Screw terminals
Width: $22.5 \text{ mm}$ (Compact design for DIN rail mounting)
Response Value ( $R_{on}$ ): $3.6 \text{ k}\Omega \pm 10\%$ (The resistance at which the relay switches off)
Release Value ( $R_{ab}$ ): $1.8 \text{ k}\Omega \pm 10\%$ (The resistance at which the relay switches back on)
Max Ambient Temperature: $-10$ to $55 \text{ °C}$
Operating Mode: Normally energised mode (The output contacts are closed under normal operating conditions)
Approvals: CE, cULus Listed, CCC

Product Advantages

Effective Overheat Protection: Provides reliable and immediate shutdown upon detecting excessive heat, which is crucial for extending the lifespan and preventing catastrophic failure of expensive motors and generators.
Versatile Power Supply: The $24 \text{ V AC/DC}$ supply voltage allows for flexible integration into various industrial control systems.
Compact Design: With a narrow $22.5 \text{ mm}$ width, it saves valuable space within control cabinets.
Flexible Outputs: The two changeover contacts (C/O) allow for simultaneous switching of the motor contactor (safety function) and sending a signal to a PLC or indicating light (monitoring function).
Sensor Monitoring: The relay monitors the thermistor circuit for short circuits, ensuring the protection function is active and reliable.

Important Considerations (Precautions)

Sensor Type: This relay is specifically designed for use with PTC (Positive Temperature Coefficient) thermistors as defined by standards like EN 44081. Using the wrong type of temperature sensor will result in incorrect or failed operation.
Safety Function: While it provides an important protective function, this device is a monitoring relay and should be used as part of a complete machine safety circuit designed according to all relevant safety standards (e.g., EN ISO 13849, IEC 62061).
Installation Environment: The device should be installed within a suitable enclosure that protects against dust and moisture, as the terminal protection rating is typically $IP20$ or lower.
Wiring and Torque: Ensure all wiring is connected securely, using the appropriate conductor cross-sections, and the screw terminals are tightened to the specified torque to prevent loose connections or arcing.
System Reset: After the temperature falls back into the normal range (below the release value), the system typically requires a manual reset or acknowledgment before the equipment can be restarted, depending on how the application circuit is designed.

Product Applications

The Pilz S1MN 24VAC/DC 2C/O is essential for applications where overheating poses a significant risk to equipment and process continuity.

Motor Protection: Primary application in protecting electric motors (especially those with internal cooling constraints or high duty cycles) from thermal overload.
Generator and Transformer Monitoring: Used to monitor the temperature within the windings of electrical generators and transformers, ensuring they operate within safe thermal limits.
Heat Process Monitoring: Monitoring the temperature in storage areas, bearings, or other equipment in industrial furnaces or ovens where excessive heat can lead to equipment damage or fire risk.
General Machinery: Integration into control panels of various machinery where heat buildup is a known hazard, such as large pumps, fans, and compressors.

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