Automatic Transfer Switches
A safe transition from one power source to another is made by means of a transfer switch. The sources can be of the type NETWORK-GENERATOR or NETWORK-NETWORK. These equipments can be configured in many ways, and depending on each need, they can be manufactured choosing the desired or required options in your electrical system. They can be manufactured under different standards:
- UL 1008 (Briggs&Stratton, ASCO, IEM brands)
- IEC 60947-6-1 (brands Telergon, Terasaki, Energy Pro)
Propace Ingeniería S.A. offers automatic or manual transfer switches with different types of transition:
- Open Transition with Delay: For applications where the sources are not controlled to synchronize, so there will always be a power failure (“blackout”) when switching from one source to the other, since there will always be a time between the opening of the breaker of a switch and the closing of the other source. These devices include mechanically and electrically interlocked switches.
- Open transition with delay and synchronism check: The control system evaluates and decides when the retransfer should be performed so that the voltage and frequency of both sources enter “in phase” and a fast switching is performed to avoid “crashes” between sources, but allows large inductive loads (such as electric motors) continue to work smoothly after a quick power outage (“very short blackout”) that occurs when switching from one source to the other. These devices include very fast-acting switches, with a maximum switch closing and opening time of 200 ms.
- Closed transition: They are used for applications where blackouts are not allowed at the time of switching. Both switches remain closed for a maximum of 100 ms, during a passive synchronism period*. The switching mechanisms or switches should act as fast as possible (openings of less than 100 ms).
*Passive synchronism: This is defined as a synchronism check. It offers the possibility to “synchronize” the mains and the genset (or any two sources) without the need for speed regulation, or rather, it offers the possibility to wait for the two sources to be in phase.
The system evaluates, according to the predefined parameters of voltage and frequency difference, and when the two sources are in phase, the system executes the switching, allowing both breakers to remain closed for a maximum of 100 ms.
The equipment takes into account delay parameters (time) in the operation of the switches so that the system computes and predicts the exact moment when the two sources enter “in phase”.