Transfer switches safely switch power from the utility grid to the generator and back, without energizing the utility lines that workers may be repairing. For those who need fast power transfers without the need to actuate a switch manually, automatic transfer switches are ideal. However, there are several types of automatic transfer switches, and this guide will help you choose the best one for your needs.
Break-Before-Make Transfer Switches
These switches offer a minimal delay during the transfer from grid to utility power, typically less than two seconds. The power from your building to the grid is disconnected first, and then the generator is connected after a short delay. This ensures that no power can be transferred from your generator to the grid. If the equipment at your business can withstand a two-second loss of power during an outage, this type of switch may be a cost-effective, reliable option.
Delayed Transition Switches
When a building has large industrial motors or other inductive loads, fast power transfers could create surges that damage sensitive equipment. A delayed transition switch prevents such damage by delaying for a few seconds in the center position when transferring between the grid and generator power or from the generator to grid power.
Make-Before-Break Transfer Switches
This transfer switch connects the generator to your building before disconnecting the grid power. Both power sources are connected only for a fraction of a second, so the danger of backfeeding and harming a utility worker is almost non-existent. This transfer switch is ideal for buildings that require constant, uninterrupted power, such as medical facilities that must power critical life-saving equipment or data centers that would suffer catastrophic data losses in the event of an outage.
Solid-State Transfer Switches
By replacing electromechanical relays with transistors, solid-state transfer switches can disconnect from the utility grid and connect to the generator with a delay of just a few milliseconds, virtually eliminating power losses or inductive surges. This switch is ideal for facilities with equipment like dimmers or motor speed controls requiring clean, constant power for reliable operation.
Which Switch is Best for Your Needs?
If the equipment at your business can stand delay, a standard break-before-make or open transition switch will be the most affordable option. Because they may be subjected to high amperage inductive loads, delayed transition switches will be a bit more costly than open transition switches, but they offer protection for businesses with large motors.
If you need fast transfers with no loss of power, the make-before-break or closed transition switch will be the best for your needs, though it is often more costly than other options. Combining the safety of an open transition switch with the speed of a closed transition model, the solid-state switch offers the best of both worlds. However, they are often expensive and more prone to failure than electromechanical switches.
Automatic Transfer Switches in for U.S. Businesses
When you need a high-quality transfer switch for your commercial or industrial facility, turn to our team at PSI Control Solutions. We feature a full line of automatic and manual transfer switches with single-phase or three-phase power and ratings from a few hundred to several thousand amps. We also offer a full range of generator accessories, from tap boxes and docking stations to load banks.
For help choosing the best transfer switch for your application, talk to our experts today by calling (704) 594-4107 or contacting us online.