PTC thermistor for Overcurrent and overload protection-MZ31 series

Reliable Overload Protection with PTC Termistor MZ31 Series

The MZ31 series PTC Termistor is a reliable component and million- time safety Termisor PTC designed for automatic circuit protection. This PTC Thermistor is commonly known as an “auto restore fuse” or “ten-thousand-time fuse.”.It provides recoverability, repeated use, and safeguards against abnormal temperature and current conditions without triggers, noise, or sparks.

PTC Termistor’s ability to self-reset makes it a durable and efficient option for maintaining circuit stability in various applications.

PTC Termistor Overload Protection Applications

The PTC Termistor from the MZ31 series is ideal for a wide range of circuit protection applications. This PTC Thermistor provides reliable protection against overloads, ensuring safety and durability in various systems.

General Applications of Termistor PTC in Circuit Protection

The MZ31 series PTC Thermistor provides reliable overload protection for sensitive electronics, such as transformers, micro motors, and control panels.

Details are as below:

• Circuit protection
• Motor overload protection
• Overload current protection
• Overload protection
• Overvoltage protection
• Short circuit protection

• Specific Use Cases of PTC Termistor

  The Termistor PTC is widely used in:

  • Transformers：It is widely used in transformers, offering automatic circuit protection for transformers and ensuring system stability.
  • Micro motors:
  • Switch power supplies,
  • Electric energy meters,
  • Chargers and adapters,
  • Apparatus,
  • Electronic coils,
  • Control panels,
  • Welding machines,
  • Home appliances, including air conditioning systems and microwave ovens etc.

  Additionally, it provides overload protection for RS485 interfaces in intelligent watt-hour meters, digital multimeters, micro motors, and transistors.

Key Advantages of Termistor PTC for Circuit Protection

The PTC Termistors offer numerous benefits in protecting circuits across various applications. Designed for reliability and efficiency, this PTC Thermistor ensures long-term performance and automatic recovery after fault conditions.

• Automatic Circuit Protection: Stable recovery after faults, ensuring minimal downtime.
• Contactless Operation: Operates without noise or flames, ensuring safety.
• Fast Response: Quickly reacts to abnormal conditions, preventing damage.
• Enhanced Overvoltage Protection: With a better performance of overvoltage protection.Suitable for a wide range of voltages.
• Low Steady Resistance: Maintains circuit efficiency with minimal power loss.
• Small Size: Easy to install in compact spaces.
• Good Stability: Reliable for long-term, continuous use.
• Automatic Recovery: No need to be reset supply after overload protection,can resume normal operation automatically.
• Termistor PTC Wide Operating Temperature Range: Operates between
•  0 ~ +60°C (V=Vmax),
• -25 ~ +125°C (V=0).
• RoHS Compliant: Environmentally friendly and safe for modern electronic systems.

• Key Features of PTC Termistor for Overload Protection

• Dimensions of PTC Thermistor MZ31 Series

   (Unit: mm)

  

Working Principle of Termistor PTC overload protection

As indicated in Fig 2 as below,when circuit is in the normal state, the current through PTC Termistor is lower than the rated current and Termistor PTC is in the normal state with small resistance value,which will not affect the normal operation of the protected circuit such as primary and secondary loops of the voltage transformer.

In case of some trouble in the circuit and the current is bigger than the rated current,the PTC thermistor will become hot quickly and present high resistance value, which sets the circuit relatively “off” to protect the circuit from damage.After the trouble is removed,PTC Termistor will automatically restore its low resistance state and the circuit will resume normal operation.

This self-regulating function makes the Termistor PTC an essential component for maintaining the safety and integrity of electronic circuits, ensuring reliable overload current protection conditions.

• Selection Guidelines of PTC Thermistor for Overload Protection

In selecting a Thermistor PTC for overvoltage and overload protection, consider the following factors:

• Maximum operating current: Ensure it matches the non-trip current of the PTC thermistor.
• Maximum operating voltage: Must meet or exceed the circuit’s requirements.
• Rated zero power resistance: Crucial for ensuring proper protection.
• Outlook and dimensions of PTC Termistor  : Should fit the design and layout of your circuit.
• Relation between operating temperature,operating current and non-operating current is as shown in Fig 3 as above.

Operating current is normally 2-3 times compared as non-operating current,and both of the currents will be reduced as operating temperature increases.

Part Number Marking

The part number for the MZ31 series Termistor PTC includes the following details:

1.Series:PTC thermistor for overload protection -MZ31 Series

2.Package Type:1-disc,2-encased,3-pin form-coating,4-pin form non-coating,5-SMD
3.Type:A-general, B-compount, C-moduie
4.Chip size: 8-Φ8mm 9-Φ9mm 11-Φ11mm
5.Curie temperature: F-50℃ H-75℃ N-100℃ P-120℃ K-125℃
6.R25 resistance: 6R0-6Ω 6R5-6.5Ω 70R-70Ω 121-120Ω
7.Resistance tolerance: K+/-10% M+/-20% H+/-25% N+/-30%
8.Greatly voltage:250-250V 265-265V
9.Wire shape: S-Straight, A-Axis formed, U-In-formed

PTC Termistor MZ31 Specifications&Part No.: