A self-protected transformer includes, from its design stage, protection elements against overvoltage, overloads and elements to isolate it from the network in case of internal or external failures.
The accessories that provide self-protection are the following:
Transient Overvoltage Protection Device, DPS (lightning arrester): Protects transformer from transient overvoltage caused by atmospheric discharges and / or swiping maneuvers, diverting them to ground.
Protection fuses
- Link: Isolation link that operates to disconnect the service transformer, in case an internal fault occurs, this element melts and prevents future re-energizations of the transformer.
- Ejection fuse: Acts as an overcurrent protection isolating the failed transformer from the network.
- Switch: Provides the transformer with a degree of protection against overloads and / or external short-circuits, either on the primary (Magnex) or secondary (Breaker) side, depending on the selected protection. They are manufactured from 10 kVA to 75 kVA single-phase and between 30 kVA and 225 kVA three-phase, complying with the NTC standard or customer specifications. They are mainly used in residential service loads and where electricity companies require load control.
The protection schemes offered are the following:
- SURGE PROTECTED SP: Provides protection against internal surges and short circuits. Includes the mounting of the DPS and the ejecting fuses. It does not include a switch for low or high voltage.
- CURRENT PROTECTED CP: Provides protection against the different types of overcurrent to which the transformer may be exposed during its operation. It is equipped with the switch (Breaker or Magnex) and protection fuses. Does not include the mounting of lightning rods.
- COMPLETE SELF PROTECTED CSP: Achieves an adequate protection against overloads, internal and / or external short circuits and overvoltage. It is equipped with the DPS, the protection fuse and the requested switch (Breaker or Magnex).
In addition, current limiting fuses can be supplied, which protect against main external short circuit currents, external power circuits and human integrity, since they disconnect the equipment from the network.