engineering fundamentals AMWEI Thermistor

AMWEI Thermistor

AMWEI Thermistor, professional manufacturer of PTC & NTC thermistors (THERMally sensitive resistors) and thermistor temperature sensors probe. PTC (Positive Temperature Coefficient) thermistor application covers over-current & overload protection, telecom, lighting switching, motor starting, temperature sensing & protection, self-regulation heating, linear PTC thermistor, silicon temperature sensor. NTC (Negative Temperature Coefficient) thermistor application covers power thermistor for inrush current suppressing limiting, NTC thermistor for temperature measurement, indicator, temperature compensation, temperature control, in either radial leaded, axial leaded or surface mount configuration. Can also make custom thermistors assemblies and temperature probes, housed in either stainless steel, copper, plastic, teflon, aluminum, epoxy and heat shrinkable tubing, such as air/gas temperature sensors, surface temperature sensors and immersion temperature sensors, etc.


AMWEI PTC and NTC thermistor has been widely applied in the field of telecom & network, HVAC & R,home electric appliance, white goods, food service, consumer electronics, lighting, office automation equipment, medical, automotive, consumer electronics, meter & instrumentation, data logger, power supply and transformer, industrial process control etc.
HVAC applications include indoor/outdoor air temperature, duct air temperature & water temperature.
Thermistor sensors play a vital part in the efficiency of white goods by measuring and controlling the temperature of water, steam, air, food, as well as the electronic circuitry.
Thermistors can be found all around the home in washing machines, dishwashers, cookers, microwave ovens, irons, toasters, refrigerators and deep freezers.
Electronic sensors offer improved accuracy over electro-mechanical solutions and can be designed to perform over a wide range of temperatures and specifications.
Food service applications include food safety, and commercial cooking equipment.
Automotive applications include climate control, fuel level/temperature, coolant & engine temperature, and combustion controls.
AMWEI Thermistor has a professional engineer team for customer’s product design and application assistance. Customer satisfaction is our honor and effort target, fast response is our pledge. 

Contact Rosa
Address 11-502, Songpingshan, Langshan Road, North Area, Shenzhen High-tech Industrial Park, Nanshan, 518057, Shenzhen, Guangdong, P.R China.
Country China
Telephone 86-755-26570111
Fax 86-755-26571122
 Showcase Products

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Linear PTC Thermistors, Silicon temperature sensors

Linear PTC Thermistor (LPTC) resistance increases with the temperature rises in linearity, displays a virtually linear temperature coefficient over their entire temperature range, suitable in measurement and control system, temperature compensation. As the construction material is mainly semiconductor monocrystalline silicon, also called silicon temperature sensor, silicon thermistor, sometimes referred to as silistors. As the temperature coefficient is positive, the silicon temperature sensors exhibit fail-safe operation when a system overheats. Furthermore silicon is inherently stable, so silicon temperature sensor are extremely reliable and have very long operational lifetimes. Hermetically sealed glass package, axial leaded, 2 leads, can operate in high temperature and moisture environment. Linear PTC thermistor in small dimension, tightness, convenient for automatic installation.

AMWEI Linear PTC Thermistor (LPTC) Features:

1. Silicon temperature sensors have a TK (temperature coefficinet) which is nearly constant over the complete temperature range. Temperature coefficient:α25/50≥0.7%/C.
2. Excellent long term stability, annual diversification rate≤0.01C/per year, temperature drifts during the lifetime of silicon temperature sensor are negligible.
3. Thermal Time Constant: 10 seconds max in still air.
4. Operating temperature range:-50~+150C.
5. Dissipation factor:2.5~5mW/C.
6. Maximum operating current:Iopr=1.0mA.
7. Rated power:10mW.
8. For AMWEI AM-LPTC600, AM-LPTC1000 part can be matched with Philips silicon temperature sensors part KTY84, KTY81.

-Sensors and Transducers > Temperature Sensors
-Test and Measurement > Sensing and Measurement Instruments
-Thermal Management > Temperature Sensors and Thermocouples

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PTC Thermistor for Overload Over-current Protection

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.

-Electrical and Electronic Components > Fuses
-Electrical and Electronic Components > Surge Protection
-Electrical and Electronic Components > Switches

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Inrush Current Limiting Power NTC Thermistors

Power NTC thermistor can be a cost effective device to limit the amount of inrush current in a switching power supply or other devices when the power is first turned on. Power NTC thermistor limits surge current by functioning as a power resistor which drops from a high cold resistance to a low hot resistance when heated by the current flowing through it.
Inrush-current limiters power NTC thermistor protect circuits from undesirably high currents, suppressing high inrush current surges, while its resistance remains negligible low during continuous operation. Thanks to their low resistance in the operating state, Power thermistor have a considerably lower power dissipation than the fixed resistors frequently used for this application.

Inrush Current Limiting Power NTC Thermistor Application

limiting surge current, suitable for the protection of switch mode power supply, UPS power, transformers, motors, various electric heating utensil, energy saving lights, ballast, various power circuit, amplifiers, colored displayer, monitors, color TV, filament protection, etc.
Power thermistor components can also be used for the soft starting of motors, for example in vacuum cleaners with continuous currents of up to 20 A.

Inrush Current Limiting Power NTC Thermistor Advantages:

·Low cost solid state device for inrush current supression.
·Minimise line current distortion and radio noise.
·Protect switches, rectifier diodes and smoothing capacitors against premature failures.
·Prevent fuse from blowing in error.

Inrush Current Limiting Power NTC Thermistor Features:

·Resin coated disk thermistor with uninsulated lead-wires.
·Suitable for both AC and DC circuits up to a voltage of 265 V(rms).
·Wide range of resistance, current and dimension.
·Excellent mechanical strength.
·Suitable for PCB mounting.

-Electrical and Electronic Components > Passive Electronic Components
-Electrical and Electronic Components > Surge Protection
-Electrical and Electronic Components > Switches

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PTC Thermistor for Temperature Protection and Temperature Sensing

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: 60~130?
·Quick response.
·Long stability.
·Small dimension, convenient for installation.
·Do not need to be reset after protection.

-Sensors and Transducers > Temperature Sensors
-Test and Measurement > Sensing and Measurement Instruments
-Thermal Management > Temperature Sensors and Thermocouples

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NTC Thermistors Temperature Sensor Probe Assemblies

NTC Thermistor can be assembled in housing in a variety of configurations for temperature sensing, measurement, detection, indicator, monitoring and control. Thermistor temperature sensor probe assemblies can conveniently attach to or be an integral part of any system to monitor or control temperature.The choice of assembly is dependent on the application. The primary factors which determine the optimum configuration of a thermistor assembly are the operating environment, mounting, time response and minimum dissipation constant.
The two factors which do vary considerably with thermistor sensor probe assembly design are time constant and dissipation constant. The time constant will typically be of greater duration in encapsulated thermistors. This is, of course, due to additional mass surrounding the thermistor element; therefore, extending the thermal transfer time. Dissipation constant will also be greater in assemblies. The additional housing mass serves well as a heat sink. Greater power is therefore required to induce self-heating. Both time constant and dissipation constant will vary with the selected thermistor and housing. Heat transfer properties of the housing, thermistor location, mass and wire type determine these constants.
Applications for temperature sensing include air temperature sensors, surface temperature sensors and immersion temperature sensors. Housings for air temperature sensors are often simple, inexpensive devices such as molded plastic shells, deep-drawn brass or aluminum cylinders, or even stainless steel tubes. Surface temperature sensors are designed to match the contour of the surface to be sensed, whether it's flat, curved, or round. Mounting holes or clips are often used to simplify installation of the sensor. Immersion temperature sensors are designed so that the sensing element will be surrounded by the medium to be sensed, often times a liquid. The sensing portion will normally protrude through a hole or orifice while a portion of the assembly will remain outside the medium to allow for the signal to be read. Immersion housings are usually threaded to allow them to be screwed into a hole or opening. Immersion part requests to be liquid and humidity prevention.
The material used for the housing will be dependent upon the temperature range needed, response time, cost, and special considerations such as UL, FDA or NSF requirements in food and/or medical applications. Some of the materials available include stainless steel, copper, plastic, teflon, brass, aluminum, epoxy and heat shrinkable tubing.

-Sensors and Transducers > Temperature Sensors
-Test and Measurement > Sensing and Measurement Instruments
-Thermal Management > Temperature Sensors and Thermocouples

Related Product Categories
Electrical and Electronic Components
Fuses protect electrical devices from overcurrents and short circuits that occur in improperly operating circuits.
Passive Electronic Components
Passive electronic components such as resistors, inductors and capacitors that do not require power to operate.
Surge Protection
Electrical devices used to detect and control high voltage or current surges in order to protect equipments or systems.
Devices used to route signals by allowing or preventing the signal flow when in closed or open position.
Sensors and Transducers
Temperature Sensors
Devices that are designed to detect or measure changes in temperature such as temperature probes, sensors, etc.
Test and Measurement
Sensing and Measurement Instruments
Instruments for the detection and measurement of physical variables such as flow, pressure, temperature, humidity, velocity, acceleration, and vibration.
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