Termistor PTC Thermistors MZ21 Series: Reliable Protection for Telecom Main Distribution Frame

Termistor PTC MZ21 Series for Telecom Circuit Protection

The MZ21 series Termistor PTC is designed to protect telecom circuits, especially for the main distribution frames (MDF).PTC Thermistors radically altered the protection requirements for both exchange and subscriber equipment.This PTC Termistor ensures reliable circuit protection for modern telecom applications.

Application and Functionality of Termistor PTC MZ21 Series

The MZ21 series PTC Thermistors are essential for protecting telecom equipment, including:

1. 1.Main Distribution Frame (MDF): Provides surge and overcurrent protection.
2. 2.Telecom Equipment: PTC Termistor protects circuits in advanced telecom systems.
3. 3.Telephone Lines: Acts as secondary protection against surges and power induction.

These thermistors are connected in series with each line, typically serving as secondary protection. Even with primary protection such as gas discharge tubes, the PTC thermistor must meet severe requirements to protect against surge pulses and power induction.

Advantages of PTC Thermistors MZ21 Series

Automatic and Reliable Protection

• Automatic Circuit Protection: Termistor PTC provides automatic, reset-free protection.
• Fast Reaction Time: Quickly responds to overcurrent, reducing damage risks.
• Noiseless and Flameless: Safe operation without noise or fire hazards.

High Performance and Compliance

• Overvoltage Protection: Operates reliably in 110/230V AC conditions.
• Low Rated Current: Minimizes power consumption.
• Long-Term Stability: Consistent performance over extended use.
• ITU-T K20 K21 Compliance: Meets global standards for surge and induction protection.

Comprehensive Protection

• Overcurrent Protection: MZ21 PTC Thermistors safeguard against surges and overcurrent in telecom lines.
• Lightning Protection: Defends circuits from nearby lightning strikes.
• Induction Resistance: Shields against alternating voltages from power lines.
• Direct Contact Safety: Prevents damage from direct power line contact.

The MZ21 series Termistor PTC provides dependable circuit protection for modern telecom equipment.

Key Features of Termistor PTC MZ21

Working Principle

The MZ21 series PTC Thermistors operate by limiting overload currents to protect circuits. In normal conditions, the PTC Termistor remains in a low resistance state. When an overcurrent occurs, the resistance increases rapidly, effectively cutting off the circuit for protection. Once the fault is cleared, the PTC thermistor cools down, returning to its low resistance state and resuming normal operation. This cycle repeats as needed, providing continuous protection.

Key Protection Actions:

1. Series Connection: Termistor PTC is connected in series as secondary protection.
2. Primary Circuit Support: Works with primary protection like gas discharge tubes to handle surges.
3. Surge Handling: Can withstand up to 2 KV surge pulses and power induction.
4. Voltage Rating: 220V-300V PTC Thermistors used with primary protection; 600V needed without.
5. Normal Operation: Stays in low resistance when current is normal.
6. Overload Response: Resistance increases sharply during overload, cutting off the circuit.
7. Post-Protection Recovery: Returns to low resistance after cooling, allowing normal operation.
8. Repetitive Protection: Automatically reactivates protection if faults reoccur, ensuring ongoing safety.

The MZ21 series Termistor PTC provides reliable, automatic protection in telecom circuits, enhancing safety and performance.

Dimensions of PTC Thermistors MZ21(Unit: mm):

Electronic feature of PTC Termistor for circuit protection of telecom apparatus:

Termistor PTC Marking of Part Number:

1.Series: PTC Thermistors for circuit protection of telecom apparatus;
2.Type:1-disc,2-encased,3-pin form-coating;4-pin form non-coating;
3.R25 resistance:55R-55;
4.Resistance tolerance:M+/-20%;
5.Non trip current(25 ℃):070-70mA;
6.Wire shape:S-straight, A-axis formed, U-in-formed;
7.Max. Voltage:250-250V.

PTC Thermistors Specification&Part no.

You can find the Specification&Part no. of Termistor PTC MZ21 Series at the bottom of this page.

Note:

1. R 25 resistance tolerance and resistance matching can be selected per customer’s requirement.
2. PTC Termistor encapsulation mode can be selected per customer’s requirement.

Conclusion on Termistor PTC MZ21 Series for Telecom Protection

The MZ21 series Termistor PTC offers crucial circuit protection for telecom equipment, especially in main distribution frames (MDF). These PTC Thermistors provide automatic protection, fast response times, and meet strict international standards. Incorporating the MZ21 series PTC Thermistors ensure telecom systems are reliable, well-protected, and resilient against modern challenges. Choose Termistor PTC MZ21 for enhanced safety and performance in demanding telecom environments.