Generator types
Standby Generator Repairs, Servicing and Testing
A standby generator is a fixed set with an automatic controller and transfer switch: when the mains fails it starts by itself, takes the load, and hands back when the supply returns. Because it may stand idle for weeks and then has to work first time with nobody there, testing matters as much as servicing. We repair, service and test the whole standby system, in any building.
- Diesel, petrol and gas standby sets of every make
- Controller, mains sensing, battery charger and ATS
- Exercise runs, simulated outages and load tests
- Load-shedding duty and back-to-back outages
Established 2006
20 years of experience
24/7 operations
We Arrive Within 1–2 Hours
(usually within 1 hour)
Free callouts and quotations
One-year warranty
Qualified and certified technicians
We Service & Repair All Generator Brands
All generator makes and models
1 kVA–20,000 kVA capability
What makes standby duty different
A standby set spends almost all its life switched off. Then, without warning and often at night, it must crank, fire, reach rated speed and voltage, and accept the load in one step. A generator that runs daily shows its faults as they develop; a standby set hides them until the outage it was bought for.
Fuel does not make a set a standby set: diesel is usual in offices, shops, clinics and server rooms, and gas suits sites with a piped or bulk LPG supply. What they share is the control system: a controller watching the mains, a battery and charger ready to crank, and an automatic transfer switch (ATS) that moves the load.
Generator servicing renews the oil, filters, coolant and battery that age even when the set does not run. A maintenance plan adds scheduled test runs between services, and generator repairs cover the engine, alternator, controller and changeover.
The readiness chain
Everything that has to work in an outage
- 01
Mains sensing
The controller watches each phase for loss, low voltage or wrong frequency. A blown sensing fuse looks like a mains failure and starts the set needlessly; sensing wired to one phase only can miss the loss of another.
- 02
Battery and charger
A mains-powered charger keeps the starting battery topped up. A dead charger can go unnoticed until the battery runs flat.
- 03
Ready to fire
Fuel, oil and coolant at level, and on larger diesels a block heater so the engine starts and takes load promptly on a cold Highveld night.
- 04
Auto-start and settle
The controller cranks, retries if the engine does not fire, and waits for voltage and frequency to settle.
- 05
Transfer and carry
The ATS moves the load to the generator, with interlocks keeping mains and generator apart, and the set carries it for hours.
- 06
Return and cool-down
Once the mains is stable, the load goes back and the engine runs unloaded to cool before stopping.
How a standby set is tested
| Test | What it proves | What it leaves unproven |
|---|---|---|
| Manual start at the controller | What it provesThe engine cranks on its own battery and runs | What it leaves unprovenAutomatic sensing, the transfer, and carrying load |
| No-load exercise run on a timer | What it provesOil circulates and the battery is used and recharged | What it leaves unprovenThe changeover and the load; repeated long no-load runs also lead to wet stacking |
| Simulated mains failure | What it provesThe whole automatic sequence on the building’s own load | What it leaves unprovenFull-rated output, when the building draws only part of the set’s kVA |
| Load bank test | What it provesThe set carries its rated load, with voltage, frequency and temperatures logged | What it leaves unprovenThe changeover, unless combined with a simulated outage |
Keep a record of each test: a slower start, a lower cranking voltage or a hotter run than last time is an early warning.
Load shedding and back-to-back outages
In the higher stages of load shedding a standby set may start two or three times a day and run two to four hours each time. A standby rating assumes limited annual hours, so a heavily loaded set running through months of this is closer to prime-power duty, and its rating is worth reviewing.
Frequent starts are hardest on the battery and starter. With outages close together the charger may not restore the battery before the next crank, so a weak battery or charger shows first as slow cranking (see battery not charging). Every outage also operates the changeover twice, wearing its contactors.
Hours-based services fall due sooner than the calendar suggests, so go by the hour meter (see service intervals and oil care). Fuel runs down faster, and each delivery stirs up water and sediment in the tank. Refuel only with the engine stopped.
Typical standby repairs
Standby system faults and where they start
No start when the mains failed: Generator not starting
Controller left in stop or manual mode after a test, a flat battery, a failed charger, an active alarm, or a mains-sensing fault.
Running, but the building is dark: ATS and changeover problems
A burnt contactor coil, a stuck motorised switch, an interlock fault, or output outside the transfer limits.
Controller alarms and timers: Control panel repairs
Fail-to-start and charge-fail alarms, and start, return and exercise timers set to suit the site. We work on DSE, ComAp, SmartGen and other controllers.
Old fuel and cold starts: Fuel system repairs
Diesel that stands for months collects water, and a failed block heater makes cold starts slow and smoky, often at the first outage of winter.
Owner checks between services
Safe to do weekly from outside the canopy and panels, without opening covers or changing settings.
- The controller shows automatic mode, with no alarm showing
- The controller or the charger’s indicator shows the battery is charging
- Enough fuel for your longest likely outage, and no leaks under the set
- Air inlets and the radiator outlet are clear of leaves and stored items
- The generator’s output breaker is on, where you can see it without opening anything
- The hour meter has moved since your last check, showing the exercise runs are happening
An automatic set can start at any moment, so keep hands out of the canopy. If anything looks wrong, call us before the next outage finds it.
FAQ
Frequently asked questions
How often should a standby generator be tested?
Many sites run a short exercise weekly or fortnightly and simulate a mains failure monthly or quarterly; the right routine depends on how critical the load is. We agree it as part of a maintenance plan.
Our standby set hardly runs. Does it still need servicing?
Yes, at least once a year. Oil and coolant age, hoses harden, diesel collects water and batteries lose capacity whether the set runs or not, and a failed charger only shows itself when the mains goes off.
Should the exercise run be on load?
Some of the time. A diesel that keeps running with little or no load runs too cool in the cylinders to burn all its fuel, which leads to wet stacking. A periodic run on the building load or a load bank burns the deposits off.
Can an existing generator be made automatic?
Often, if it has electric start. It needs an auto-start controller and an ATS wired into the distribution board by a registered electrical contractor. A pull-start-only unit cannot start itself.
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