Generator transfer switches are what actually make backup power work. You can have the best generator in the world, but if the transfer switch isn’t doing its job, you’re still sitting in the dark when mains power drops out.
If you’re setting up backup power or your existing generator transfer switch is playing up, here’s what you need to know.
What a Transfer Switch Does
When mains power fails, the transfer switch detects it and switches your load over to generator power. When mains comes back, it switches you back. Simple concept, critical function.
The switch monitors mains supply constantly. Power drops out, transfer switch starts your generator and waits for it to reach proper voltage and frequency. Once the generator’s running properly, switch transfers the load over.
When mains comes back and stabilises, switch transfers you back to mains and shuts the generator down after a cooling period.
All happens automatically without anyone needing to do anything.
Manual Versus Automatic
Manual transfer switches need someone to physically operate them. Power goes out, you’ve got to manually switch to generator power. Pain in the backside, especially at 2am.
Automatic transfer switches sort it themselves. Power fails, switch starts the generator and transfers load automatically. Power returns, switches back and shuts generator down.
For critical applications, automatic is essential.
Two-Pole Versus Three-Pole
Single-phase supplies need two-pole transfer switches. Three-phase supplies need three-pole units.
Using wrong type causes problems. Won’t switch properly, might not provide proper isolation, could create dangerous situations.
Match the transfer switch to your supply type. Don’t bodge it.
Load Rating Matters
Transfer switches are rated for specific current loads. Your switch needs to handle your maximum load plus safety margin.
Under-rated switch will overheat, contacts will burn out, you’ll have failures at the worst times.
Work out your actual load requirements properly. Include starting currents for motors, not just running loads.
Bellwood Rewinds can help with load calculations.
Changeover Time
How fast does the transfer switch actually switch? This matters for some applications.
Most automatic transfer switches take a few seconds. Generator needs time to start and reach proper voltage before load gets transferred. Typically 10-30 seconds.
For loads that can’t tolerate any interruption, you need different solutions like UPS systems. Standard transfer switches have brief interruption.
Know what your equipment can tolerate.
Installation and Wiring
Transfer switches need proper installation by qualified electricians. This isn’t DIY territory.
Incoming mains, generator supply, outgoing to load, all need correct wiring. Control connections between transfer switch and generator need sorting. Earth connections are critical.
Wrong installation creates dangerous situations. Live parts exposed, incorrect earthing, faulty control wiring can kill people.
Use proper electricians who understand generator systems.
Testing and Maintenance
Transfer switches need regular testing to make sure they’ll actually work when needed. Monthly tests are typical.
Test cycle includes starting the generator, transferring load, running briefly, transferring back, shutting down.
Contacts need periodic inspection. Control circuits need checking. Neglected transfer switches fail when you need them most.
Bellwood Rewinds offer maintenance contracts for generator systems.
When Transfer Switches Go Wrong
Common problems include contacts burning out from excessive load or poor maintenance. Control circuit failures preventing automatic operation. Mechanical issues stopping changeover.
Faulty transfer switch might not start the generator when mains fails. Might not transfer load properly. Might not switch back to mains.
Regular maintenance and proper load sizing prevent most problems.
Getting Proper Transfer Switches
Not all transfer switches are equal. Quality units from proper manufacturers last years. Cheap rubbish fails quickly.
Brands like Socomec, ABB, Eaton, Schneider make reliable transfer switches. Bellwood Rewinds stock and install quality units matched to your requirements.
For critical backup power, the transfer switch is as important as the generator. Get quality kit, install it properly, maintain it regularly.
Your backup power system’s only as reliable as its weakest component.
