Minggu, 10 Juli 2011

Transformer isolation and its use

isolation transformer is an isolation transformer is designed to overcome the problems associated with internal insulation to ground reference. It is built with two rolls of Faraday isolation between primary and secondary windings.

isolation transformer secondary winding having the same amount with the primary winding, so the secondary voltage is equal to the primary voltage. But in some designs, the secondary winding is made a bit more to compensate for the loss. This transformer serves as insulation between the two prop. For audio applications, the transformer of this type have been largely supplanted by the coupling capacitor.

When installed properly, insulation, closest to the primary winding, is connected to ground power supply and the isolation of the most common close to the secondary winding is connected with the isolation circuit to be isolated. The use of two shields in the construction of an isolation transformer for the transfer of high-frequency noise, which will usually be incorporated in the transformer

Both shields provide more effective isolation of primary and secondary circuits by also isolating their reasons. Transformer isolation adds the third capacitance between the two Faraday shield, which can allow high frequency noise coupling between the base system. However, increasing the separation between the two Faraday shield to minimize this capacitance is usually the third. In addition, the effect of the dielectric shield plus separation increased significantly reduce the capacitance roll-between between the rolls.

Transformer isolation and its use

isolation transformer is extensively used in medical equipment, telecommunications equipment, remote control equipment, computers & peripherals, CNC machines, analytical instruments, etc.
Losses in the transformer

Copper losses. I2.R copper losses in the windings caused by the resistance of copper and electrical currents flood.

Coupling losses. Losses incurred due to the primary-secondary coupling is not perfect, so not all the induced magnetic flux cutting the coil primary secondary. These losses can be reduced by rolling in multi-layered winding between primary and secondary.

Capacity loss is wild. Losses caused by wild capacity contained in the winding-winding transformer. These losses greatly affect the efficiency of the transformer for high frequency. These losses can be reduced by rolling the primary and secondary windings are semi-random (winding banks).

Hysteresis losses. Losses that occur when the primary AC current U-turn. Due to core transformer can not change the direction of the magnetic flux immediately. These losses can be reduced by using low reluctance core material.

Skin effect losses. As with other current-carrying conductor alternating, currents tend to flow on the surface of the conductor. This enlarges the capacity loss and also increase the relative resistance of the coil. These losses can be deducted by using Litz wire, the wire consists of several small wires are mutually insulated. For the radio frequency used geronggong wire or thin
copper sheet instead of regular wire.

Eddy current losses (currents megrim). Losses caused by emf input that causes the current in a magnetic core that is against the change of magnetic flux that generates an emf. Because of the magnetic flux is changing, there wake of magnetic flux in the core material. This loss is reduced when used multi-layer core.

Tidak ada komentar:

Posting Komentar