Telecom PTC Thermistor Description
This series of ceramic 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.
Typical Application of PTC Thermistor in Telecommunication Protection
Central Office Switching Equipment (C.O), analog and digital line cards, T1/E1 equipment, xDSL modems and splitters, multiplexers, CSU/DSU, servers.
Primary Protection Modules, MDF (main distribution frame) modules, network interface devices (NIC).
Custom Premises Equipment, also known as subscriber terminal equipment (T.E.), IT equipment: Modem, phone sets, fax machines, phone wall outlet (plugs), alarm systems, answering machine, PBX systems, ADSL Splitters, internet appliance, POS terminals.
Access Network hardware, LAN WAN equipment, Powered Ethernet systems, VoIP (voice over IP equipment), Set-top box (S.B), etc.
Telecom PTC Thermistor Features
Compliant with ITU-T K20 K21 K45
Basic level lightning surges (10/700ª¦s)
Basic level power Induction (600V,1A,0.2S)
Power contact criteria A/B (230V,15min.)
Suitable for continuous connection to main voltage 110/230 VAC in tripped (high ohmic) condition.
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Liquid Cooled Charging Cables are electric vehicle charging cables that utilize liquid cooling to achieve high-speed charging. These cables feature a 500A current rating and a 1000V voltage rating for charging speeds up to 500KW.
PTC thermistors current protector, also called PTC thermistor resettable fuses, protect load against over-current, overload, short circuit. No need for replacement, resume protective function after a short cooling-down time. 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. Operating Principle of PTC Thermistor for Overload Over-current Protection The operating principle is as indicated in the following. When a circuit is in the normal status, the current through PTC is lower than the rated current and PTC thermistor protector is in the normal state with small resistance value, which will not affect the normal operation of the protected circuit. In case of some fault in the circuit and the current is greater than the rated current, the PTC thermistor protector will become hot quickly and present a high resistance state, which sets the circuit relatively "off" to protect the circuit from damage. After the fault is removed, PTC thermistor protector will automatically restore its low resistance state and the circuit will resume normal operation. Normally, when PTC thermistor is used as an overcurrent protection component, it is preferred to select maximum operating current, maximum operating voltage and proper specifications. Furthermore such factors should be taken into consideration as the dimensions of the components, rated zero-power resistance, operating temperature range, etc.
PTC thermistors current protector, also called PTC thermistor resettable fuses, protect load against over-current, overload, short circuit. No need for replacement, resume protective function after a short cooling-down time. 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. Operating Principle of PTC Thermistor for Overload Over-current Protection The operating principle is as indicated in the following. When a circuit is in the normal status, the current through PTC is lower than the rated current and PTC thermistor protector is in the normal state with small resistance value, which will not affect the normal operation of the protected circuit. In case of some fault in the circuit and the current is greater than the rated current, the PTC thermistor protector will become hot quickly and present a high resistance state, which sets the circuit relatively "off" to protect the circuit from damage. After the fault is removed, PTC thermistor protector will automatically restore its low resistance state and the circuit will resume normal operation. Normally, when PTC thermistor is used as an overcurrent protection component, it is preferred to select maximum operating current, maximum operating voltage and proper specifications. Furthermore such factors should be taken into consideration as the dimensions of the components, rated zero-power resistance, operating temperature range, etc.
Temperature Protection PTC Thermistor Description PTC (positive temperature coefficient )thermistor switches at one particular temperature. Making use of the characteristics that the resistance of PTC thermistor increases sharply above curie temperature, when ambient temperature increases abnormally, protective circuit installed PTC thermistor will turn on or cut off loop through resistance changing, achieving thermal protection purpose. PTC thermistor protect such equipment and components as motors, transformers, power transistors and thyristors against over-temperature. A PTC thermistor is less expensive than a thermostat, and its switch temperature can be more accurately specified. It is also smaller and easier to design-in to electronic circuitry. Therefore PTC thermistor can be ideal devices for temperature detection, monitoring, indicating, limiting and over (excessive) temperature protection. Typical Application of PTC Thermistor for Temperature Protection and temperature limiting sensors Limit temperature measurement of Industrial electronics application. Power supplies, switch power supply. Home appliances, such as dish washers, washing machines, ironing machines, electric cookers, etc. Electronic data processing and communications engineering (DC/DC converters). Motor windings overheating Protection. Automotive electronics. Semiconductor heatsinks, enclosure panels, temperature-limited transistors. Lighting applications. Features of PTC Thermistor for Temperature Protection and temperature limiting sensors 2 Outlook construction: A-radial leaded epoxy resin coated form, B-metal tag lug form. PTC Thermistor Protection temperature: 60-130C Quick response. Long stability. Small dimension, convenient for installation. Do not need to be reset after protection.
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