Isolation transformer usage and precautions

Any transformer with two or more independent coils can be called an isolation transformer, because the primary and secondary are completely separated (isolated) and energy is transferred through the magnetic field.

Since after separation, people can no longer be connected to the "mains power live wire", it becomes relatively safe.

As for the 50W power and the short circuit, first of all, it should be explained that short circuits must be avoided absolutely, and the greater the power, the more it must be avoided. The greater the power, the shorter the time the transformer can withstand short circuits! Because after a short circuit, the power will increase sharply (usually several times or dozens of times the rated power), and it will be damaged quickly.

However, switching power supplies or high-frequency transformers are not necessarily afraid of short circuits, because they are generally designed with protection circuits.

In addition, isolation does not mean absolute safety, because the output voltage of an isolation transformer with a transformation ratio of 1:1 (or smaller) may be higher than 36V. When you touch two wires at the same time, current will still flow through your body.

Why use an isolation transformer?

First of all, we need to understand my country's power supply system. When supplying low-voltage users, my country's power supply system generally adopts a three-phase four-wire system with a grounded neutral line. In layman's terms, the wires to residents' homes have one phase line (live wire) and the other is the neutral line, which is at the same level as the earth. When the human body touches the hot base, the current will pass through the human body and form a loop with the earth, causing an electric shock hazard. If an isolation transformer is used, it will be safer because the primary and secondary exchange energy through the magnetic field and there is no physical hard connection. Even if the human body touches a live object, the potential of the live part will be low because the human body and the earth are at the same level, and will not cause an electric shock hazard.

There are two points to note when using an isolation transformer

1. Both ends of the secondary of the transformer cannot be grounded.

2. The human body cannot touch both ends of the secondary at the same time, otherwise there is a risk of electric shock.