XIAN XIWUER ELECTRONIC AND INFO. CO., LTD
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PTC,which is used as over current protection,is ought to selected to fit for the Max,non-operating current and Maximum voltage.Formal Dimension of elements,Rated zero power resistance and the range of application temperature should be also considered.Usually,1.2-1.5 times of the maximum working current is selected as the Max.Ptc non-operating current when the circuit works normally.The voltage befell on PTC in normal or abnormal states of the circuitry shouldn't Non-operating Current exceed the Maximum working voltage.
Features
Applications
Thermistor is mainly applied in abnormal current and thermal protection of electronic ballast(energy-saving lamp,electronic transformer,multimeter,intellectualized ammeter etc.).It can be in series of the load circuitry right and clamp the excessive current or interdict the current automatically in exceptional conditions,and come back the primary state automatically after the trouble eliminat:
PTC thermistor transformer overvoltage and overcurrent protection principle
The principle of overvoltage and overcurrent protection is shown in Figure 1. In the electronic watt-hour meter, the transformer over-voltage protection means that when the electronic watt-hour meter is working normally (conventional 220-300VAC), the normal operating current is small, generally below 50mA, and the thermistor It works normally under this current, and the resistance value is low, which will not cause abnormal effects on the front-end voltage divider. When the front-end voltage of the grid is too high, or the plug-in voltage causes the front-end voltage of the transformer to be too high (greater than 320VAC), the current at the input terminal increases, reaching the thermistor protection current, increasing the resistance of the thermistor, and then It increases the voltage drop on the thermistor, and acts as a voltage divider protection function for the transformer, so that the electronic watt-hour meter does not burn out due to excessive voltage.
Figure 1 Load
| Model | Nominal Resistance Range at 25 °C Rn(Ω) | Switching temperature (°C) | Non-operating current (mA) | Operating current (mA) | Dimensions (mm) | |
| Dmax | Tmax | |||||
| MZ21 -04BC(200-400) Ω | 200-400 | 90±7 | 10 | 35 | 5.5 | 5.0 |
| MZ21-04BC(400-700) Ω | 400-700 | 90±7 | 8.5 | 30 | 5.5 | 5.0 |
| MZ21-04BC(500-800)Ω | 500-800 | 90±7 | 8 | 30 | 5.5 | 5.0 |
| MZ21-04BC(800-1200)Ω | 800-1200 | 90±7 | 6.5 | 25 | 5.5 | 5.0 |
| MZ21 -04BC( 1000-1500) | 1000-1500 | 90±7 | 6.0 | 20 | 5.5 | 5.0 |
| MZ21-03BB301H | 300±25% | 100±7 | 10 | 50 | 4.5 | 5.0 |
| MZ21-03BB(300~450) Ω | 300-450 | 100±7 | 10 | 45 | 4.5 | 5.0 |
| MZ21-04BB( 100-200) Ω | 100-200 | 100±7 | 20 | 55 | 5.5 | 5.2 |
| MZ21-04BB( 200-300) Ω | 200-300 | 100±7 | 18 | 45 | 5.5 | 5.2 |
| MZ21-04BB( 300-450) Ω | 300-450 | 100±7 | 15 | 40 | 5.5 | 5.2 |
| MZ21-05BB( 150-250) Ω | 150-250 | 100±7 | 25 | 65 | 6.5 | 5.5 |
| MZ21-05BB301M | 300± 20% | 100±7 | 20 | 60 | 6.5 | 5.5 |
| MZ21-05BB122M | 1200± 20% | 100±7 | 18 | 50 | 6.5 | 5.5 |
| MZ11-08BB(130-190)Ω | 130-190 | 100±7 | 25 | 80 | 8.5 | 5.5 |
| MZ21-05AR(200~400)Ω | 200-400 | 115±7 | 25 | 80 | 6.5 | 5.5 |
| MZ21-05AR(300~600) Ω | 300-600 | 115±7 | 20 | 70 | 6.5 | 5.5 |
| MZ21-05AR(500~800)Ω | 500-800 | 115±7 | 15 | 60 | 6.5 | 5.5 |
| MZ21-05AR(700~1000)Ω | 700-1000 | 115±7 | 10 | 50 | 6.5 | 5.5 |
| MZ21-05AR(900~1200)Ω | 900-1200 | 115±7 | 8 | 40 | 6.5 | 5.5 |
| MZ21-05AR( 1000-1500)0 | 1000-1500 | 115±7 | 6 | 30 | 6.5 | 5.5 |
| MZ21—08AR(150-250)Ω | 150-250 | 120±7 | 35 | 90 | 8.5 | 5.5 |
| MZ21—08AR(90-160)Ω | 90-160 | 120±7 | 40 | 120 | 8.5 | 5.5 |
| MZ21—08AR(65-100)Ω | 65-100 | 120±7 | 50 | 150 | 8.5 | 5.5 |
| MZ21—08AR(45-70)Ω | 45-70 | 120±7 | 60 | 200 | 8.5 | 5.5 |
| MZ21-10AR(20-40)Ω | 20-40 | 120±7 | 80 | 250 | 10.5 | 5.5 |
COMPANY OVERVIEW
Xian Xiwuer Electronic & Info. Co., Ltd. is located in Beiguan, Xi'an city cover in an area of 4000 ㎡, with employees of 2300, and about 580 technicians, amongthem, there are 135 engineers, 21 senior engineers. The company has total assets of 315 million RMB Yuan, fixed assets of 137 million RMB Yuan, which is a large enterprise mainly engaged in producing electronic components.
The company has the largest production scale of Varistor,SPD( Surge Protective Device)and HV Ceramic Capacitor in China, with the following main products :
1. Varistors & SPD
4. Thermistor
The main production line and inspection equipment & instrument are imported from Japan, America, Belgium and Switzerland etc. The annual production capacity of the two leading products has been reached to 5 million pcs and 150 million pcs respectively, with the market holding rate in China of about 10% and 30% respectively by continually technical innovation. Varistors and SPD produced by the company enjoyed great reputation in the international market, being exported to many countries and areas such as Japan,USA, Hong Kong etc., with the customers like India and GE in USA. are already sold to LG company in Korea with large quantity, and also to Spainand India etc.
Not only the products quality and technical capacity, but also the completeness of the models are all in the leading place in China. The main products have got CCEE, UL, VDE & TUV approval. The quality system was set up according to the requirement of ISO9000 since 1992, and has passed ISO9002 approval by DNV International Organization in July 1994, then got ISO9001 certification by British organization in 2000, by then we are both the first one who are approved by ISO9000 certification in the North-west area of China and the same occupation. We passed all the successive periodical audit and smoothly get the new certificate registered in Holland in Aug.1997; the quality system is strengthened and completed constantly. And we also got ISO18000 certificate.
We believe we are able to supply satisfied goods and service to customers home and abroad with the most reasonable price and the shortest delivery time, on basis of our excellent quality assurance capacity, technical development capacity and rich manufacturing experiences.
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