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  • Article source - | Author - Administrator | Hits - | Published - 2013-09-26 09:20:43
    WH PPTC in a small transformer application plan


         The main function of the transformer: voltage conversion; impedance transformation; isolation; stable voltage, etc., commonly used in a variety of power among a small charge circuitry. The main failure mode short circuit, open circuit.
    2,The new generation transformer characteristics?

         1, in order to reduce costs, power margin designing smaller, fast heating;
         2, the application of copper is small and can only work properly, easily large currents blown.
         3, the limit on the cost reduction in the strength of enamelled only meet the specified application, easy to   crack, high temperature aging, internal short circuit.
         4, limiting costs resulting core loss, high fever situation.
    3, Why special protection of the transformer?

         Between the above characteristics, the transformer becomes very fragile, easy in application due to damage, mainly due to the damage of the transformer primary over-voltage, the secondary circuit, overcurrent. This will cause the transformer of the "copper loss" (current flowing through the coil of the heat consumption) and the "iron loss" (from "vortex" loss generated) surge in a short time and cause the coil temperature;, and cause an overcurrent is usually due to a short circuit or reverse polarity; such a large loop current. The transformer coils usually relatively thin in a large current through the heating coil, the temperature rises above a certain temperature (the majority of our class A power transformer insulation, coils allowable temperature is 105 ℃, under normal case, the transformer top oil does not exceed 85 ℃, maximum does not exceed 95 ℃), melting coil insulating paint outside, so easy to short circuit and even lead to smoke, fire, so that damage to the circuit components will be a corresponding portion of the associated an overload or work overload situations. Severe cases can lead to failure because of overheating, so that local circuit damage.
    4,How to protect the transformer?

        People usually in the primary circuit in series thermal fuse (thermal fuse) or in the secondary circuit in series electrical fuse (fuse) to protect the transformer. The biggest drawback of this program is that it uses a one-time protection components. If the fuse blows, the transformer will subsequently scrapped, thus greatly improved by increasing the equipment maintenance costs. The circuit breaker having recoverability another overcurrent in the circuit mode, but it cost too much, so not all of the circuits are suitable for use. Some dual metal fragments road protection, its limitations in that it does not exclude the fault in the case repeatedly turned on; and its protection is limited to temperatures have been working for some time (about 50 seconds), the transformer insulated coil has produced damage; this is very dangerous, therefore we recommend to do the application WHPTC resettable fuse transformer protection devices, can avoid the above-mentioned lack of protection methods.
    5,Why Recommended Applications WHPTC resettable fuse to protects the transformer?
       1, with self-reset function WHPTC resettable fuse could satisfy both transformers for over current, over temperature protection, automatic reset, and low cost requirements.
       2, WHPTC can limit the maximum temperature of the coil in the lower levels, while WHPTC self-recovery fuse lower surface temperature.
       3, WHPTC resistance and volume is relatively smaller, and is less susceptible to vibration, shock, rapid temperature change causes damage. Visible WHPPTC for transformer overcurrent, overtemperature protection has a unique advantage.
       4, WHPTC self-resetting overcurrent protection device, having minimal resistance under normal operating conditions, in the event of failure or when there is interference pulse rapid action, fast response time, the resistance of the circuit in a sharp rise in isolation protection status, broken power automatically reset without replacing, reducing maintenance costs.
       5, applied to small charger transformer particularly vulnerable to reverse battery, short circuit currents generated by large burn, WHPTC reversed in the battery, short circuit occurs quickly and timely protection against battery discharge and the charger damaged.
    6. WHPTC resettable fuse application advantages?

    7. WHPTC transformer protection applications in the installation location and process recommendations




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