Prevention of electric shock using insulation transformer
The second side is grounded because of safety though the primary side and the second side of the transformer on the pillar are insulated. The way things are going, when the second side is touched, it is likely to get an electric shock. Then, the insulation transformer might be used further for the electric shock prevention.
Usual electric shock of circuit that doesn't use insulation transformer
The high pressure of 6600V has been converted into 100V or 200V of the domestic use with the transformer on the utility pole in left figure. The second side of this transformer and the core of the transformer are grounded.
100V in the voltage of ground is generated in a domestic both terminals of one side and 200V of 100V because the transformer on the pillar is grounded. When the person touches the metallic portion of the exterior when insulation worsens and the V of the exterior of the product of the appliance hangs to the metallic portion 100(When the appliance leaks electricity in a word), it gets an electric shock as shown in this drawing in a word. At this time, a lot of currents (current leakage and ground-fault current) might flow when feet from which the person is standing is damp and the person die.
Electricity flows to the earth even if the person touches the metallic portion of the exterior if in this case, there is a good earth for the appliance and the human body is safer. Moreover, the leak breaker of the switchboard works by the thing that this current of the earth (current leakage and ground-fault current) flows and it cuts off the power supply.
It is likely to get an electric shock like this only by touching the one side of home appliance and the power supply that leaks electricity in a general domestic 100V power supply circuit that doesn't use the insulation transformer.
Electric shock prevention circuit using insulation transformer
It is a further insulation transformer in 100V power supply like left figure to prevent the electric shock like the above-mentioned (separates transformer) might be used.
In this case, the power supply of 100V on the side is insulated from 100V and the earth circuits of the first side further with the second insulation transformers.
Therefore, it doesn't get an electric shock, and the leak breaker on the first side of the insulation transformer doesn't work because the current doesn't flow anywhere only by touching the one side of home appliance and the power supply that leaks electricity either.
If the circuit is intercepted by the leak, such a circuit is used for the place where an embarrassed hospital and an important circuit and the electric shock are prevented. In addition, to prevent the electric shock, it grounds it to an electric equipment (earth).
Reason to use insulation transformer (purpose)
Prevention of electric shock
Even if the electric equipment used by any chance becomes an insulation failure, the electric shock can be prevented. However, when two electric equipment become the insulation failures at the same time with two electric equipment or more, it is likely to get an electric shock. The electric shock can be prevented if it grounds it to an electric equipment in this case.
When the energized part of 100V circuit is touched while repairing, it gets an electric shock when a transformerless appliance of the television etc. is repaired. The insulation transformer is effective also for the prevention of this. (The high pressure cannot be prevented being gotten an electric shock. )
This is a power supply insulated with the insulation transformer though the hospital grade mains socket outlet is used in ICU, the operating room, and the recovery room in the hospital. This power supply is called non-grounding link method (floating power supply).
It always observes whether it is not or very the equipment that the isolation monitor (insulation level monitoring device) is set up on the second side of non-grounding link method of the hospital and insulation is bad.
There is the one that became non-grounding link method though this photograph is an outlet (It comes off, it stops, and addition the earth) for the emergency because the outlet is red, too.
Prevention of interception of sudden circuit
When the insulation transformer is not used, the leak breaker might work when one electric equipment leaks electricity and all power supplies intercept it. When medical equipment as important as the hospital is used, the insulation transformer is used because it embarrasses it when the power supply cuts suddenly.
Moreover, electricity leaks when the antenna terminal is hit to the charge part when a transformerless appliance of the television etc. is repaired and the leak breaker of the switchboard cuts. The insulated antenna terminal is used or if this insulation transformer is used for the power supply, this can be prevented.
Stability of equipment operation
Because the insulation transformer enters on the way of the power supply, the noise from the power supply can be decreased. Therefore, an electric equipment can work with stability. In addition, to operate with stability, we will recommend an electric equipment to be grounded by the beeline.
When this insulation transformer exists, radio-frequency signal (4MHz-28MHz) is not transmitted because the information signal is put on a domestic electric wiring (electric power line) and it sends it in PLC (high-speed electric power line communication) recent adaptor. This signal is seen from the electric power and the noise.
The first potential on the second side can be set besides the side.
The insulation transformer can set the first potential on the second side regardless by the translation from which the first side and the second side are insulated as the side. For instance, one side and the neutral point on the second side can be grounded, and it is also possible to make it to the potential of direct current that it is low to make the second side the potential of direct current that is higher than the grounding potential.
Notes of circuit using insulation transformer
In the circuit using the insulation transformer, it is necessary to note it because the leak breaker of the switchboard doesn't operate by the leak. It is necessary to set up the leak breaker on the second side of the insulation transformer to intercept the circuit by the leak. However, the leak breaker doesn't work if not leaking electricity in two places or more.
Please note the electric shock when an external metallic portion of an electric equipment of one of terminals on the second side of the insulation transformer and another insulation failures is touched when there is an electric equipment of the insulation failure on the second side of the insulation transformer. To prevent the electric shock even in this case, it grounds it to an electric equipment.
It is needless to say to the electric shock when feeling after both terminals of 100V power supply at the same time with an insulation transformer.