AMWEI - Model 25 Ohm 250V 1A - PTC Thermistors for Overcurrent Protection in Telecom Applications, Leaded Disk Coated

Resistance @25C  R25 : 25Ω,
Standard R25 tolerance +/-  20%, tight tolerance +/-  15% can be supplied upon request.
Rated voltage (RMS) : 230 V
Maximum operating voltage Vmax: 250 V
Maximum withstanding voltage: 350V
Maximum permissible repetitive turn over current Imax: 1 A
Non-trip Current at +25C : 85 mA
Non-trip Current at +40C:  75 mA
PTC Thermistor Trip Current, Operating Current at +25℃ It : 170 mA
Tripping time at +25C:  1A→ 0.5A: < 0.7 seconds.
Operating ambient temperature range (V=0): -40~+125C
Operating ambient temperature range (V=230V) :  0~60C

Compliant with ITU-T standards

basic-level lightning surges (10/700 µs)
basic level power induction (600 V, 1 A, 0.2 s)
power contact criteria A/B (230 V, 15 min.)
Matching available with narrow resistance tolerance.
Tight resistance matching maintained after switching.
Negligible resistance drift after soldering or switching.

Cross to  EPCOS obsolete B59069B1120A051, GE RL1605-25-120-50-PTF.

Overcurrent protection for telecom applications
Suitable for line card applications e.g. POTS, access networks,
customer premises equipment (CPE) or integrated voice data (IVD)

Ceramic positive temperature coefficient PTC thermistor help provide protection against power cross, power induction surges and lighting surge defined in ITU, Telcordia, UL.

This thermally sensitive semiconductor resistor provides reversible, self-resetting fuse protection against over-currents short circuit for telecommunication line protector units, improve the reliability of custom premises and network equipment.

Advanced developments in telecom equipment in recent years have radically altered the protection requirements of both exchange and subscriber equipment. PTC Thermistor Current Protector 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 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。

More details in Ceramic PTC Thermistor for Telecom High Voltage Current Surge Protection .

Reference information: How to Choose PTC Thermistors to Protect Telecom Equipment and Installations: Ceramic vs. Polymer?