Electric networks are a complex ramified engineering structure. Taking into account the fundamental need to transmit electricity at high voltage (up to hundreds of kV), and its use at a sufficiently low (220 and 380 V), as you approach the consumer, you have to lower voltage. Physically, this procedure is carried out on the so-called. substations, the key component of which is a power step-down transformer with associated fittings.
Technical means of increasing the operational reliability of the substation and the consequences of their failure
The normal operation of the substation is ensured by numerous auxiliary subsystems, one of which is responsible for the protection of equipment and people in the event of various emergencies. The equipment forming it, which is assembled from electromechanical relays for various purposes (time, power, etc.) and their electronic counterparts, operates in an automatic mode.
This equipment is mounted in cabinets, Figure 1 and solves the problem of shutting down the emergency section or preventing the very cause of the emergency.
Relay protection often contains several thousand individual components, it is a full-fledged complex technical system that has the ultimate operational reliability. To increase it, a backup system and duplication of various critical nodes are used. Nevertheless, it is impossible to achieve 100% protection against accidents, primarily from short circuits on the line.
By virtue of its very purpose, the substation is characterized by high voltages and high currents. Therefore, the failure of protection in the event of a short circuit leads to the release of very high power on transformers and switches. The latter is immediately converted to heat.
Functions of the main means of insulation of live parts, ensuring normal temperature conditions when normal operation and protection from moisture in these elements is performed by degassed and dried transformer oil. In the event of a short circuit, it boils, which leads to the ejection or even explosion of the tank and the subsequent ignition of the oil vapors. Due to the large volumes of oil, the fire usually becomes very serious, Figure 2, and its consequences are quite severe, Figure 3.
Why there should be no unauthorized persons at the substation
The distribution substation of the lower levels of the electrical network belongs to unattended facilities. The absence of personnel is accompanied by the risks of various persons entering its territory, incl. out of natural curiosity, which can lead to:
- high voltage electric shock;
- failure of expensive equipment
- interruption of power supply of a large number of real estate objects.
Given the severity of these consequences, a number of measures are being taken to protect substations.
The main ones are:
- allocation of a separate area with appropriate fencing;
- application of clearly visible and understandable warning labels;
- organization of means of remote control against penetration.