What is the Purpose of an Isolation Transformer?
Isolation transformer is the transformer with electrical isolation between the input winding and the output winding. Isolation transformer is used to avoid users accidentally touching the charged body at the same time. Isolation transformer, whose transformer ratio is usually 1:1, is a special transformer with high insulation strength between the primary winding and secondary winding to isolate different potential to suppress common mode interference.
Isolation transformer is the safety power supply, generally used for machine repair and maintenance, and plays the role of protection, lightning protection, filtering. The principle of step-up & step-down isolation transformer is the same as that of ordinary transformer. They all use the principle of electromagnetic induction. Because the secondary coil is not connected to the ground and there is no potential difference between any secondary line and the ground, isolation transformer is safe to use and often used as a maintenance power supply.
The main function of the step-up & step-down isolation transformer is to completely insulate the primary side and the secondary side, and also to isolate the loop. In addition, the high frequency loss of the iron core is used to suppress the high frequency clutter into the control loop. The use of isolation transformers to allow levitation of the secondary to the ground can only be used in situations where the power supply range is small and the line is short. At this point, the capacitance current of the system to the ground is too low to harm people. Another important function of step-up & step-down isolation transformer is to isolate the hazard voltage for protecting personal safety.
With the development of power system, transformer plays an increasingly important role as the key equipment in the power system. Its safe operation is directly related to the reliability of the entire power system. Transformer coil deformation refers to the axial and amplitude dimension changes, body displacement, coil distortion and other situations that occur when the coil is under stress. There are two main reasons for transformer coil deformation: one is that the transformer is inevitably impacted by external short circuit fault in operation; the other is that the transformer has an accidental collision in the process of transportation and hoisting.
In order to ensure personal safety and avoid some unnecessary losses during maintenance, it is best to connect a 1:1 isolation transformer to AC 220V circuit between the mains and the power input end, so as to prevent electric shock (shown as figure 1). If oscilloscope, scanner, signal generator or other equipment is used to detect the circuit, the ground wire of the three-core power plug line of these equipment should be disconnected (shown as figure 2). In addition, the power supply can not be no-load during maintenance, and must be added around 280 Ω dummy load for inspection.