PTC Thermistor and NTC Thermistor Technology

MZ12A PTC thermistor is mainly used for over-current and over-heat protection of electronic ballasts (energy-saving lamps, electronic transformers, multimeters, smart electric meters), etc.

PTC thermistor for filament preheating

1. Application scope:
It is used in various fluorescent lamp electronic ballasts and electronic energy-saving lamps. There is no need to change the circuit. Just connect the appropriate thermistor directly across the resonant capacitor of the lamp tube. The hard start of the electronic ballast and electronic energy-saving lamp can be changed to preheat start, so that the preheat time of the filament can reach 0.4 to 2 seconds, which can extend the life of the lamp tube by more than three times.

2. Features:
Made of PTC material, the product has small size, high voltage resistance, long life and low power consumption during normal operation.

3. Application principle:
The principle of preheating start-up by using PTC thermistor is shown in the figure on the right: When the switch is just turned on, Rt is at room temperature, and its resistance is much lower than that of C2. When the current passes through C1, the self-heating temperature of Rt exceeds the Curie point temperature Tc and jumps into the high-resistance state. Its resistance is much higher than that of C2. The current passes through C1 and C2 to form a loop, resulting in LC resonance, generating high voltage to light the lamp.

Fuse-type PTC thermistor

1. Application scope:
MZ12A PTC thermistor is mainly used for overcurrent and overheat protection of electronic ballasts (energy-saving lamps, electronic transformers, multimeters, smart electric meters), etc. It is directly connected in series in the load circuit. When the line is abnormal, it can automatically limit the overcurrent or block the current. When the fault is eliminated, it will return to its original state. It is commonly known as "ten thousand times fuse".

2. Features:
· Contactless circuit and component protection · Automatic overcurrent limitation
· Automatic recovery after fault elimination · No noise and spark during operation
· Reliable operation and easy to use

3. Application principle:
Connect the PTC thermistor in series in the power supply circuit. When the circuit is in normal state, the current flowing through the PTC is less than the rated current. The PTC is in normal state and the resistance is very small, which will not affect the normal operation of the protected circuits such as electronic ballasts (energy-saving lamps, transformers, multimeters). When the circuit current greatly exceeds the rated current, the PTC suddenly heats up and the resistance suddenly increases to a high resistance state, thereby limiting or blocking the current and protecting the circuit from damage. After the current returns to normal, the PTC automatically returns to a low resistance state, and the circuit resumes normal operation.

In the field of overcurrent protection applications such as electronic ballasts (energy-saving lamps, transformers, multimeters), Nanjing Shiheng, relying on its advantages in scientific research and technology, took the lead in launching the MZ12 product featuring high withstand voltage (V≥300VAC).

Preheating start with zero power consumption
1. Application scope:
MZ11B series PTC thermistors are mainly used for preheating start with zero temperature rise and zero power consumption of high-performance ballasts and energy-saving lamps.
2. Application principle:
MZ11B series PTC thermistors are actually a composite component of a PTC thermistor Rt in series with a varistor Rv. When powered on, the voltage is higher than the Rv varistor voltage, and Rv is in the on state. The preheating start process is basically completed independently by Rt. After the lamp is started and lit in normal working state, the voltage quickly drops to the Rv varistor voltage, and Rv is in the off state, so that zero power consumption and zero temperature rise can be achieved.

The selection of the MZ11B series is basically similar to that of the MZ11A series, except that the Rv varistor voltage should be slightly higher than the lamp voltage.

Power NTC Thermistor

1. Product Introduction
In order to avoid the surge current generated in the electronic circuit at the moment of power-on, a power type NTC thermistor is connected in series in the power circuit, which can effectively suppress the surge current when the power is turned on. After the surge current is suppressed, due to the continuous action of the current passing through it, the resistance value of the power type NTC thermistor will drop to a very small level. The power it consumes can be ignored and will not affect the normal working current. Therefore, using a power type NTC thermistor in the power circuit is the simplest and most effective measure to suppress the surge when the power is turned on to protect the electronic equipment from damage.

2. Application scope
Suitable for protection of power supply conversion, switching power supply, UPS power supply, various electric heaters, electronic energy-saving lamps, electronic ballasts, power circuits of various electronic devices, and filament protection of color display tubes, incandescent lamps and other lighting fixtures.

3. Features:
· Small size, high power, strong ability to suppress surge current
· Fast response speed
· Large material constant (B value), small residual resistance
· Long life, high reliability
· Full series, wide working range