PTC Series:

1. MZ2 Series for overcurrent protection in telecom
2. MZ31 Series for time delay starting for lighting
3. MZ6 Series for thermal protection
4. MZ7 Series for degaussing component of colour TV set and monitor, current-limited unit in AC circuit
5. MZ4 Series for Auto Control Component on air conditioner, hot wind machine and varies of heater., for Auto control components on small heater, rooling hair machine, driving mosquito machine
6. MZ32 Series for non-tounched switch in cold compressor and motor.

Common Glossary:

Rate Zero-power Resistance (Rn):DC resistance value of the thermistor measured under 25℃ by adopting sufficiently low power consumption.

Maximum Operating Voltage (Vmax) The maximum rated voltage the PTC thermistor can continuously endure at 25℃.

Maximum Inrush Current (Imax) The maximum current (effective value) through the PTC thermistor under max.rated voltage. Exceeding this current may result in damage to the PTC components.

Reference Temperature (Tsw) The temperature at which the resistance value of the PTC thermistor increases to twice Rmin, also called Curie temperature.

Non-trip Current (Int) Rated current or holding current, at maximum operating temperature, this is the maximum current value that doesn't trip the PTC to the high resistance state. Under these conditions, PTC performs as a fixed resistor.

Trip Current (It) The minimum current value that will cause the PTC to trip to the protective high resistance state.

Operating Temperature Range The ambient temperature range in which PTC can be used when the maximum voltage is applied. Range is -10℃to+60℃.

Temperature Coefficient of Resistance(a_T) The Temperature coefficient is calculated from the linear range at the steepest portion of resistance (Tb-Tp) as illustrated in Fig.1. a_T=(InRp-InRb)˙100/(Tp-Tb) (%/℃)

Dissipation Factor (δ)  The ratio power dissipation change to temperature change of PTC thermistor(in mw/ ℃).  δ=p/(T-Tr)

                         Where P=dissipation power              

T=thermistor body temperature

Tr=room temperature

MZ2 Series for overcurrent protection in telecom

Advanced developments in telephony equipment in rencent years have radically altered the protection requirements for both exchange and subscriber equipment. The PTC thermistor must protect the telephone line circuit against overcurrent, which may be caused the following examples:
◆ Surges due to lighting strikes on or near to the line plant.
◆ Short-term induction of alternating voltage from adjacent power lines or railway systems ,usually caused when these lines or systems develop faults.
◆ Direct contact between telephone lines and power lines.

To provide good protection under such conditions a PTC thermistor is connected in series with each line, usually as secondary protection; see Fig.1. However, even with primary line protection (usually a gas discharge tube ),the PTC thermistor must fulfill severe requirements.

Surge pulses of up to 2 KV can occur and in order to withstand short-term power induction the PTC thermistor must withstand hign voltages. If the line has primary protection, a 220V to 300V PTC thermistor is adequate. Without primary protection,600V PTC device is necessary..

Fig.1                         Fig.2             Fig. 3          Fig. 4

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MZ31 Series for time delay start for lighting

 MZ31 series of PTC Thermistor are applicable to various types of fluorescent lamp, electronic ballast and electronic energy-saving lamp. The PTC can be connected across the lamp resonator without changing the circuits. It can change hard start of the ballast and electronic energy-saving lamp to preheated start and the preheating time of the filament can come up to 0.4-2 seconds, which will extend the service life of the fluorescent tube by over 3 times.

The application of the PTC thermistor to achieve preheated start is as follows: Immediately after power is switched on, Rt is in normal temperature state and its resistance is far lower than the C2 resistance. The current through C1 and Rt forms a return circuit to preheat the filament. After about 0.4-2 seconds, Rt joule heat temperature exceeds Curie point Tsw and skips into high resistance state of far higher than C2 resistance. The current passes through C1 and C2 to form a return circuit, which causes L resonance and produces high voltage to light the fluorescent tube

Fig.1 Examples of applications                Fig.2 Component outline

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MZ6 Series for thermal protection

 MZ6 series as a temperature indicator is small in size and little in calorific capacity. It is so useful for indicating any overheating of power transistors and thyristors in the power sources.

Fig.1 Componect outline                          Fig.2 Resistance vs.Temperature Characteristics

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