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Product specification:
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 by 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 system,usually
caused when these lines or systems occur 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 high voltages. If the line has primary protection, a 220V to 300V PTC thermistor is adequate. Without primary protection,600V PTC device is necessary. Ampron manufactures a series of PTC thermistor fulfilling both requirements.
1. MZ23 is resin leading-wire type , MZ25 is non coating leading-wire type, MZ26 is patch type
2. fulfill ITU-T K20 K21
   current impact(10/700μs)
   electric high voltage induction(600V,1A,0.2S)
   wire lap(230V,15min.)
3. suitable for continuous work 110/230VAC
4. small resistance tolerance
5. long term stability
6. fast response
7. re-setting isn’t need after overload protection