Normally Static Transfer Switches are used for data centres, aviation, defence, industrial, or other high value commercial projects. One of our customers is using the STS to undertake peak lopping.
In this case the application is associated with a Gospel / Recital Centre. The building is in a residential area where there is insufficient street power available and the cost for providing the reticulation would have made the project prohibitive.
The Gospel Centre can cater for up to 2000 people and is typically used just once a week for a few hours. The rest of the time the hall is rented out for much smaller social gatherings by clubs and community meetings. On Sundays and some other religiously important calendar events the street power capacity is insufficient to supply the demand of the air-conditioners, lights, amplification systems etc. (Street capacity being limited to less than 200 Amperes, the maximum demand often exceeds 600 Amperes).
To supplement the demand the site rented and installed a 500kVA generator. Once the load exceeds the street capacity the generator is automatically started and a Static Transfer Switches (product code i-STS630Ks3P4), transfers seamlessly to the generator supply for the duration of the event. As the event winds down and the power demands falls to that which the street mains supply can support, the Static Transfer Switch transfers back to the street supply. All without the slightest flicker due to the fast transfer / change-over that a Static Transfer Switch supports. The alternative implementation of ATS (Auto Transfer Switch) would have meant that the lights would have gone out, air-conditioners shutdown or re-cycled and most importantly the sound systems would have had to be interrupted. In fact the implementation was so successful that the organization installed this scheme to another 3 sites.
Because the generator is not operating at the same frequency as the mains, all transfers using the Static Transfer Switch occur when the supplies pass through synchronism, meaning the change-over occurs at zero current. As such the change-overs are completely transparent to even the most critical of load elements. This is undertaken using the Static Transfer Switches standard controls (preferred source section), supply failure/ return detection and a simple current based load / overload relay.
This opens up a whole new category of usage in the renewable energy field and where the existing infrastructure has been outgrown.