Automatic start-up of the standby power supply is required to ensure continuous power supply to the equipment in case of emergency failure of the main power source.
An additional set of busbars or a spare transformer are used as a backup power supply. To ensure uninterrupted power supply, it is important to provide not only the availability of backup power, but also a mechanism for safe load transfer to the backup device. For this purpose, special high-tech automatic standby switching schemes have been developed. They also make it possible to prevent damage due to short interruptions in power supply. The use of ATS is mandatory at almost all production facilities. They are installed:
- In control panels and control racks.
- In transformer substations.
- In steam generators (water and oil pump control mechanism).
Auxiliary transformers, which are used for standby power supply, have high performance. Special requirements are placed on automatic standby input devices supplying electrical installations with high voltage in constant current mode.
High-voltage electrical installations with operating direct current
Requirements for automatic reserve switching:
- The connection of the synchronous electric motor must take a minimum of time. There must be no dead time.
- The system must be switched on once and only after switching off the toggle switch.
- The emergency power supply must not be started if an unauthorised power failure was accompanied by a short circuit.
Correct operation of the equipment requires ATS model with functions of maximum current protection of the network and protection against voltage drop to the minimum level. The maximum current protection can be provided at the main power supply source. If the operating and backup sources cannot operate in parallel, protection failures may occur due to non-synchronous operation. In this case, the parallel operation must be blocked, i.e. the operation of the operating and standby sources must be independent and manual switching of modes must be ensured after successful tripping of the standby switch-on. There may also be an option to lengthen the dwell time for a complete switching cycle.
Depending on the category of the industrial facility, single-relay or dual-relay systems are used. Single-relay systems are used in category III plants, with an automatic standby switching system installed at each input.
Category I and II plants are equipped with two sets of relays. In case of malfunctions in the supply network or transformers, this mechanism prevents false tripping, e.g. in case of conductor breakage. Voltage transformers are installed at the backup inputs, the main input is equipped with busbar transformers.
Electrocity has been on the market since 2006. During this time we have successfully realised many projects on installation of automatic standby switching systems.
