供应MF72－突波限流NTC热敏电阻

华龙的NTC热敏电阻器系由*配置的金属氧化物陶瓷材料制成，它可用来抑制高的突波电流。相对于受保护电路,热敏电阻器具有较高的电阻。因此会抑制突波电流约1~2秒，在这一段时间内热敏电阻的电阻将因温度升高而下降，直至热敏电阻两端压降到可被忽略的电阻值为止。如图A以电源供应器为例,在电源开的*，电容器一般阻**低，桥式整流器通常承受很大的电流，热敏电阻器*使用于保护电源供应器。

HUALONG electronic NTC Thermistor devices are made of a specially formulated metal oxide ceramic material which is capable of suppressing high inrush current surges.

Thermistor devices, being of relatively high resistance, shall limit the inrush current for 1~2 seconds during which time the device decreased in resistance substantially to a point where its voltage drop is negligible .The devices are especially useful in power supplies (see Fig A) because of the extremely low impedance of the capacitor being charged, of which the bridge is ususlly subjected to an exceedingly high current surge at turnon point.

特质：

●*抑止突波电流。

●稳定状态下功率损耗*小(通常*有1W或小于50W)。

●热及电特性稳定性高。

●宽广的电性规格可供选择。

●High inrush current restriction effect

●Small power loss in stationary state

●(Normally less than 50W power)

●High thermal and electrical stability.

●Wide selection of electrical performances

如图B所示，将一NTC热敏电阻与一白热灯丝串联时，可以消除突波电流。若一只NTC热敏电阻无法提供*之突流限制功能时，二只或更多的热敏电阻可用于串联电路上或供应电路的各个分路上(如图A)。但要注意的是NTC热敏电阻，不可并联于电路上，因为其中一只NTC就可能会传导几乎*的电流。热敏电阻*好用于图A所示AC电路的A1或A2处，或是DC电路D1或D2处。

在设计上，当电路刚被打开的*，NTC热敏电阻的阻值高于电路上*白热灯丝的总电阻值。当电流开始通过时，热敏电阻*产生「自然」现象，并在1到2秒内，阻值会降到几可忽略。以同样的构想来看电动马达的突波电流，亦可以被抑制到限度。图C表示应用热敏电阻保护直流马达前后突波电流波形的差异。

As shown in Fig.B, the current surge can be eliminated by placing a NTC thermistor in series with a filament string. Yet, if the resistance of one NTC thermistor does not provide sufficient inrush current limiting functions for your applicantion, 2 or more may be used in series or in separate legs of the supply circuit (Fig.A). Be noticed, the thermistor can not be used in parallel since one unit will tend to conduct nearly all the current available. Thus, thermistor may be used in the AC (point A1or A2)or the DC (point D1or D2) locations in the circuit. (see Fig.A)

The resistance of NTC thermistor is designed higher than the total resistance of NIC thermistor is designed higher than the total resistance of filaments when thermistor shall immediately self-heat. Then, in 1~2 seconds, its resistance will be reduced to a minimum and become insignificant to the total resistance of a circuit. With the same concept, current surges in electric motors can be held to minimum. Fig.C shows a t*ical DC motor's turn on surge before and after the application of a thermistor to the circuit

1.热敏电阻器的*大工作电流＞实际电源回路的工作电流

2.热敏电阻器的标称电阻值

R≥        式中E为线路电压 l m为浪涌电流

               对于转换电源、逆变电源、开关电源、

               UPS电源l m=100倍工作电流

               对于灯丝、加热器等回路l m=30倍工作电流