PTC Thermistor for Overload & Over-current Protection

Product Description

Current Protection PTC Thermistor Description
Ceramic PTC (positive temperature coefficient) thermistors are used instead of conventional fuses to protect load, such as motors, transformers, or electronic circuit, against overcurrent for circuit protection. PTC thermistor protector not only respond to inadmissibly high currents but also if a preset temperature limit is exceeded. PTC thermistor over-current protector limits the power dissipation of the whole circuit by increasing their resistance and thus reducing the current to a harmless residual value. In contrast to conventional fuses, PTC thermistor resettable fuses do not have to be replaced after elimination of the fault but resume their protective function immediately after a short cooling-down time.

PTC Thermistor Over-current Protector Application
It applies in the over-current overload and short circuit protection of transformers, battery charger, switches, switch power supply, adaptor, meter, instrumentation, apparatus, electronic coils, control panels, air conditioner, automotive electron, etc.
R25 Resistance: 0.5-5000 ohm
Maximum Operating Voltage(Vmax): 12-650 V
Non-trip Current(Int): 5-7000mA
Diameter: 3-22mm

Telecom PTC (positive temperature coefficient ) thermistors help provide protection against power cross, power induction surges and lighting surge defined in ITU, Telcordia, UL. Available in chip, radial-leaded coated and non-coated, SMD, twin vertical surface mount configuration. PTC thermistor overcurrent protector provides reversible, self-resetting protection against over-currents of telecommunication line protector units, improve the reliability of custom premises and network equipment.
Ceramic PTC thermistors can be found providing re-settable line protection at the exchange, monitoring hot spots and protecting ringers, battery feeds, transformers and relay circuits. Also used extensively to protect the mobile phone's battery pack against overcharging in land-based and radio mobile communications.

Advanced developments in telecom equipment in recent years have radically altered the protection requirements of 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 adjactent 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; However, even with primary line protection (usually a gas discharge tube), the PTC thermistor must fulfill severe requirements.
Surge pulses of upto 2KV 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. We can manufacture a series of PTC thermistor fulfilling both requirements.
R25 Resistance: 8-220 ohm
Maximum Operating Voltage(Vmax): 110-650 V
Non-trip Current(Int): 40-180mA

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