A: The size of generator you buy should be based on the type and number of appliances, pumps, air conditioners and other electrical devices in your home or business.
A load calculation is the most accurate way to determine just how many watts/amps your home/business uses and is the basis for an accurate choice of generator size.
If you need to power air conditioning units, well pumps, welders etc. It is important that your load calculation is carried out correctly. Electric motors may require up to four times the running watts to start the motor. When calculating the load requirement, all electric motors should be added using their start up watt requirements.
Q: What is a transfer switch?
Q: What does the term 'engine slobber' mean in reference to a diesel engine?
Q: I want the generator to power a computer system and server in my home or business. Are there any issues with this?
Q: Can I use an auto start, or automatic transfer switch with a portable generator set?
Q: What is the purpose of the electronic control unit on the generator set?
Q: What kind of maintenance will a diesel generator require?
Q: 3,000 or 1,5000 rpm, what's the difference?
Q: Do I need a single or a 3-phase alternator?
Q: What size generator should I buy?
A: A transfer switch is a manual device which allows power to be supplied to the distribution panel from the mains/utility supply, or the generator supply, but not both at the same time.
An automatic transfer switch will constantly monitor the voltage of the mains/utility supply (or each phase of a 3 phase supply). In the event of a power outage or deep brown out, the control panel will automatically transfer the load of your home or business from the mains/utility supply to the generator.
A: If you have a 3 phase service, you will need a 3 phase alternator. Most residential applications operate on a single phase supply and although it is possible to reconfigure a 12 wire 3 phase alternator to supply single phase power, if you only require single phase, you will lose approx 30% of the potential by using a 3 phase alternator in a single phase configuration. Reconfiguring a 3 phase alternator to single phase will also increase your fuel costs.
In short, if you have a single phase service, use a single phase alternator. If you have a 3 phase service use a 3 phase alternator.
A: A 3,000 rpm alternator has two poles (the number of magnets on the rotor, a 1,500rpm alternator has 4 poles). 3,000 rpm alternators are normally portable (3 to 10kw approx) and air cooled. They are manufactured to keep weight and cost down and as such are designed for short term use and have a relatively short life span. If you experience frequent outages, long outage times and for a longer life-span, a 1,500 rpm generator, powered by a liquid cooled diesel engine would be a more suitable choice.
A: Diesel engines require routine maintenance for long life service. The service requirements are similar to those of owning a diesel vehicle; periodical change of the oil, oil filter, air filter and fuel filter.
The engine will require an oil and oil filter change every 500 hours if used regularly, or annually in the case of a standby generator. Air filters should be changed when they appear dirty (or blow them clean if you have a compressed air supply). Radiator coolant and fuel filters should be checked and/or changed when you carry out the oil change. You should also carry out a periodical check of the radiator fan belt, checking for any signs of wear and for adequate tension.
A: Most modern generator control units are digital and are designed to control the generator set functions. The controller will monitor the operation of the engine and monitor oil pressure, water temperature, over/under speed (frequency), coolant level etc. If the controller has an auto start option, it can be used in combination with an automatic transfer switch to start and stop the generator automatically in the event of a power outage.
A: Generally, No. Most portable generator sets do not have the capability to start automatically. To do so a generator must have an electric starter, start/stop controls and safety sensors. The addition of auto start and safety sensors increases the price of portable equipment so much that it becomes less commercially viable and as such they are not manufactured.
A: The electricity supply from a generator is regulated to avoid fluctuations in voltage and provide clean power. Most modern diesel generators incorporate an automatic voltage regulator (AVR), this is an electronic module providing voltage regulation in the 1 to 2% range and will normally meet or exceed the local utility power specifications. Some smaller, portable generators use capacitor voltage regulation, delivering voltage regulation in the 5% to 10% range and can present a problem for some computer systems. If you are in any doubt, we would advise you to plug your computer and/or server into a battery regulated power supply (UPS), which will provide additional voltage regulation to that provided by your generator supply.
A: Diesel generators are designed to operate with a load. When a generator operates considerably below the rated output level, the engine can start to over fuel. Ideally, diesel generators should run at around 65-80% of their maximum rated load. When a generator operates for prolonged periods below 40% of the rated output, it begins to over fuel, the injection tips begin to carbonize and disrupt the fuel spray pattern. This poor combustion leads to soot formation and un-burnt fuel residue which clogs and gums piston rings. This causes a further drop in sealing efficiency and exacerbates the initial low pressure.
This problem can be avoided by ensuring that your generator is correctly sized. If your generator is run up regularly simply to test its operation, it should be placed on load and not run off load.