Transformer is the main function: voltage transform; impedance transformation; isolation; stable voltage, commonly used in a variety of power supply, small charger circuit. The main failure mode of short circuit, open circuit.
2. A new generation of transformer characteristics?
1, in order to reduce the cost, smaller power margin design, fast temperature rise;
Application of copper wire 2, smaller, only can work normally, be in current fuses.
3, costs limited enameled lower intensity, only to meet the specified application, easy cracking, high temperature aging, internal short circuit.
4, limit the cost to lead core loss, high fever cases.
3. Why should the transformer special protection?
Between the above characteristics, transformer becomes very fragile, easy in application because of the damage, the damage is mainly due to the primary transformer overvoltage, short circuit, over current. This will make the transformer " copper loss " ( current flowing through the coil of the heat consumption ) and " iron " ( from " eddy " the loss ) in a short period of time to increase, and causes the coil temperature rise, resulting in excessive current flow; the cause is usually a short circuit or polarity reverse connection; this kind of loop current change. But the transformer coil usually relatively small, in the large current through, coil heating, temperature, above a certain temperature ( China electric power transformer for a majority of insulating material, coil allows the temperature of 105 ℃, under normal circumstances, the transformer top oil does not exceed 85 ℃, highest do not exceed 95℃coil ), outer insulating paint melting, so easy to short circuit, and even lead to circuit, fire smoke, so that the damaged circuit associated components and there will be a overload or overload condition. Serious when can overheat and fail, make local circuit break.
4. How for transformer protection?
Usually people in primary line in series thermal fuse ( fuse ) or in the secondary line in series electrical fuse ( fuse protecting transformer current ). This scheme is the biggest drawback is that it uses a disposable protective element. If the fuse links, the transformer will be discarded, thus greatly increasing the cost of equipment maintenance. Recoverable circuit breaker circuit is additionally an over-current protection, but its cost is too high, so not all the circuits are suitable for use. Some uses the double metal sheet breaker, its limitation is that it is in the fault is not eliminated in case of repeated connection; and it is protected in a limited temperature has been working for a long time ( about 50 seconds), on the insulation of the transformer coil has produced damage; this is very dangerous, so we recommend application WHPTC self recovery fuse for transformer protection element, can avoid the shortage of the protection method.
5. Why recommend using WHPTC self recovery fuse protecting transformer?
In 1, with automatic reset function of WHPTC can satisfy the transformer on over-current, over-temperature protection, automatic reset, low cost requirements.
In 2, WHPTC can be used to the maximum temperature of the coils in the lower level of restrictions, while WHPTC's surface temperature lower.
In 3, WHPTC resistance and volume smaller, and less prone to vibration, impact, rapid temperature change and other reasons and damage. See WHPPTC for transformer over-current, over-temperature protection has unique advantages.
In 4, WHPTC self-resetting overcurrent protection, is in the normal working condition resistance minima, in the event of a failure or a disturbance pulse can move quickly, quick response time, sharp increases in resistance circuit isolation protection state, power automatic reset without replacement, reduce maintenance cost.
In 5, applied to small charger transformer special for battery reverse connection, short circuit current of large burn, WHPTC in battery reverse connection short circuit occurs, prompt protection, avoid over discharge of battery, charger damage.