In IT systems, all active components are isolated from earth or connected to it through a high impedance. This high impedance may be necessary for metrological reasons, provided that it does not compromise electrical safety. The earthing of the electrical installation grounds can be done individually or together.
How do IT systems differ from TN and TT systems?
In TN systems, the neutral point of the power transformer is connected to earth with a low impedance, and the electrical installation grounds are linked to this earthing system by means of a protective conductor. In TT systems, the neutral point is also connected to earth with a low impedance, but the electrical installation grounds have their own independent earthing system, separate from that of the system.
Did you know that the electrical diagram you choose can make the difference between safe operation and the risk of serious failure? Choosing the right electrical connection diagram is crucial to ensure that an installation operates safely and reliably. The main objective is to protect people and equipment, avoiding electrical hazards or fires, and ensuring that the installation remains operational at all times.
What are the different connection schemes?
There are three types of connection scheme: TN, TT and IT. Of these, the IT system has a special advantage: if a first insulation failure occurs, it does not cause the system to disconnect. This means that the system can continue to operate without interruption, which is crucial in environments where no downtime can be allowed.
Why is the IT system so important?
Nowadays, installations are increasingly complex and automated. From production lines to robotic equipment, many processes depend on a constant power supply. In sectors such as hospitals, the use of IT systems is regulated by standards to ensure that medical equipment continues to operate continuously, even if there is a failure in the electrical system.
What happens if you don’t choose the right scheme?
An inadequate electrical system can cause service interruptions, affecting people’s safety and the operation of essential equipment. With the IT system, you can rest assured that the electrical supply will remain stable, reducing the risk of failure and guaranteeing continuity of operation.
The IT (isolated) system is characterized by its ability to maintain the electricity supply in places where continuity of service is crucial.
1. Isolation from earth:
- All active components of the electrical system (such as transformers, generators, etc.) are isolated from the ground. This means that the neutral of the transformer, although theoretically isolated, is connected to the ground by the parasitic capacities of the network cables or by means of a high impedance (approximately 1500 Ω).
- This characteristic is fundamental to prevent an insulation failure from causing a total interruption of the electrical service.
2. Direct connection of the masses to earth:
- The masses of the system, such as the metal parts of the equipment, are directly connected to earth, which guarantees the safety of the system against possible insulation failures.
- In the event of contact with a live mass, the circulating current is minimal, which considerably reduces the risk of dangerous electric shocks.
3. Safety and continuity:
- Due to the insulation, if an insulation fault occurs, the IT system does not stop the power supply, which is crucial for maintaining the activity of critical installations. This allows hospitals, for example, to continue operating normally, even during an insulation fault.
- The fault current and conductor resistance are very low, minimizing contact voltages and preventing the risk of electrocution.
4. Constant monitoring:
- IT systems must have an insulation monitor, a component that connects the active network conductors to the ground. This monitor allows for the detection of and alerts about an initial fault between an active component and the ground, facilitating rapid intervention before the fault becomes a bigger problem.
The IT system is essential in hospitals and healthcare facilities, where the continuity of the electrical service is crucial for the safety and well-being of patients. These facilities require a constant electrical supply for the proper functioning of medical equipment, monitoring systems and other vital areas.
Some of the most important applications in the healthcare sector are described below:
- Hospital operating rooms: In operating rooms, where complex surgical procedures are performed, interruption of the power supply could endanger the patient’s life. The IT system ensures that all essential equipment, such as vital sign monitors, ventilators, surgical lighting systems and respiratory support devices, continue to function continuously, even in the event of a power failure.
- Intensive care units (ICUs): ICUs, where critically ill patients are treated, depend on medical equipment that requires a constant power supply. Monitors, respirators and infusion pumps cannot be stopped, so an IT system ensures the continuity of these essential services, avoiding risks to the patient’s health.
- Emergency power systems: In hospitals, the IT system is also used in emergency power systems, such as generators and batteries, which guarantee the supply of energy during power cuts. This is crucial to maintain the operability of life support equipment and other essential facilities, such as refrigeration systems for medicines or blood.