Questions about IT systems

N is the neutral wire, also known as the zero wire. The IT system provides 3-phase 380V; if 220V is required, a 380/220 transformer must be used to generate that voltage. The entire system is powered by suspension.

Reply to 2# blmin: Thank you for the reply. Does this mean that systems with direct grounding, such as TT and TN types, are more suitable for 220V low-voltage power supply?

Reply to 3# Ocean Engineering Studio: Yes, since the IT system does not have an N wire, it is only possible to connect single-phase electrical devices with a rated voltage equal to that of the system’s line voltage. The exposed conductive parts of all devices in the system are grounded separately through their respective PE wires. This system is primarily used in areas where continuous power supply is essential and where there is a risk of fire or explosion! !

Does this mean then that only the TT and TN systems, which are systems with direct grounding, are more suitable for 220V low-voltage power supply? The IT system can also generate a 220V voltage through voltage transformation, and it is primarily used in the coal industry.

Reply to 4#: It’s not available in street markets. Why can’t it be used in flammable and explosive environments?

If the power supply of an IT system is not grounded or is grounded through impedance, the exposed conductive parts of electrical equipment can be directly grounded or connected to the power supply’s grounding conductor via a protective wire; this is also known as protective grounding. Within the lT system: 1. The live conductors of electrical equipment are insulated from ground, or the neutral point of the power supply is grounded through a high impedance ； 2. All exposed conductive parts and the external conductive parts of the device are grounded through the grounding electrode of the electrical device. Since the fault current is low when the system experiences its first failure, no dangerous contact voltage is generated on the metal enclosures of the electrical equipment; therefore, it is possible to keep the electrical equipment running without shutting down the power supply, and the fault can be resolved through alarm devices and inspections. The power supply should be automatically cut off in the event of a second fault within the IT system: when a second fault occurs on another phase wire or the neutral wire, the fault must be eliminated promptly.

It is drawn out together with the power source and the three phases; current can flow when the three phases are unbalanced! IT is defined as follows: I represents the wiring method at the power supply terminal ； T represents the wiring method at the load side