PTC Thermistor

Prroduct introduction

The MZ32 series Surge suppression series is a type of surge peak current suppression used in high power switching lines to protect power devices and filter capacitors.

High capacity capacitors are used in various power supply lines to smooth and filter the DC voltage after rectification. 

If it is discharged during startup, a short circuit will occur, affecting the rectifier and the power line. 

Some inductive loads, such as large transformers or engines, can also produce too high an impulse current. 

In the worst case, extremely high impulse currents can damage the rectifier or blow the power fuse.

In addition to the impulse current, another danger manifests in excessive continuous current or short circuit of equipment. 

Typically, this risk comes mainly from defective loop capacitors or power semiconductor devices. 

With the MZ32 series thermistors, these risk sources can be eliminated. Unlike negative temperature coefficient impulse current limiter, 

positive temperature coefficient thermistors have positive temperature characteristics, that is, lower resistance at room temperature. 

The current increase will gradually increase the temperature of the positive temperature coefficient thermistor, bringing it into a high resistance state, 

thus limiting the current. These ceramic parts are like self-resetting fuses: once the current surge recedes, 

the temperature of the resistor will decrease and the PTC will return to a low-resistance conductive state.

 

Typical application diagram of PTC for current surge limitation

The filter capacitance is calculated according to the following formula

(Unit：uF)

C: Filter capacitor

Tc:PTC Curie temperature

V: Capacitor charging voltage (V=1.414xVs)

0.7: safety factor

Ta: ambient temperature

Enon60=0.7x(Tc-Ta)xCth         Enon60: Maximum inactive energy at 60 degrees (Ta=60)

PRODUCT FEATURES

1. MZ32 series products are divided into two categories: A-chip type, B-shell type, C-coating type

2. High resistance voltage: 120V-500V

3. Long-term stability

4. No mechanical and electrical noise

5. No contact

6. High energy

APPLICATION

1. Household appliances (air conditioning, refrigerator start)

2. High-power switching power supply

3. Inverter