Power outages

The after-effects of an adverse event can see power outages and significant disruption to tasks we take for granted as priorities on NZ dairy farms.

Occasionally major faults at substations or with transmission lines some distance away can cut power and may take considerable time to repair.

What will a power outage mean for the farm?

Farms rely on power for daily activities. Providing water to animals, keeping lights on, and maintaining a prime environment through heating water and cooling milk are all activities that require electricity. As a result, losing power to the farm can mean a loss of animals and revenue.

• No electric fences: Have stock in paddocks away from roads, unsafe areas on the property, winter crops or silage paddocks etc.
• No pumps: Access to clean water is a priority for stock and humans. Water contaminated with silt, ash, etc can be toxic to stock, so troughs may need to be emptied and cleaned. Stormwater will accumulate if the drainage pump doesn't operate.
• No milking: Cows can tolerate going for extended periods without milking, but it is best to avoid delays if possible. See the section on Missed Milkings.
• No refrigeration: If milk already in the vat cannot be cooled to the required temperature you may have to use an emergency disposal method. See the section on Missed Milkings.
• No hot water: milking machine cleaning and other operations may have to be changed.

Do you have access to a generator?

A generator large enough to power the milking machine and ancillary equipment is expensive but may be a good investment if your property is prone to flooding, snow or other causes of power outages. They provide peace of mind to farmers by providing backup power in the case of emergencies.

Without generators, modern agriculture faces many challenges in the case of a power shortage or outage. Generators provide electricity to areas that are not able to access the primary power source.

Small generators that power domestic appliances or small pumps start at around $500. Something large enough to run the dairy including refrigeration could be around $30,000. Generators can be hired from hire centres.

A backup generator is extremely useful in the event of a power outage. Generators come in a vast range of power outputs. The high power demand on a farm makes it especially vulnerable during power outages.

Large standby generators are specifically designed for use as backup power supplies in operations that require strong, reliable power. These heavy-duty units are equipped with large fuel tanks to enable them to run continuously for many hours and even days.

Smaller portable generators provide convenient and reliable power for lighter energy needs and shorter periods. They are very effective in supplying small appliances, lights, and computers with power. Many farmhouses use portable generators to provide a power supply to the families who live on the farm – keeping them safe, warm and operational during a power outage.

A frequent dilemma that farmers face is that the main source of power is restricted to certain parts of a farm, making off-site operations almost impossible without a portable power supply. A portable generator offers the perfect solution as it is a handy and reliable source of power which can be taken to any job site.

Small petrol generators can be used for low-demand energy supplies, like providing light or running small power tools. Larger, portable diesel generators are lightweight but robust and powerful, which make for economical, but effective use - even on jobs with tough power demands.

Prime power supplies are used as a fixed or main power source to operate continuously or at an extended amount of time. These generators provide plenty of watts and work well at remote sites where there is no, or very limited, access to main electricity supply grids. This makes them especially useful on large farms or farms in remote areas of the country.

Many farms use these large stationary generators in situations where there are limitations on the amounts of power that can be used from the main supply, or where the power supply is easily overloaded. In some instances, it can be cheaper to use a prime power generator instead of electric power from the main power supply.

Sizing a generator

Getting a generator that can handle all your power generation needs is one of the most critical aspects of the purchasing decision. Whether you are interested in prime or standby power, if your new generator can’t meet your specific requirements then it simply won’t be doing anyone any good.

Diesel generators

For any application where the generator is going to run and provide power for more than a few appliances and lights then diesel generators are superior to petrol generators.

PTO generators

With PTO generators you will already have the motor so the generator is relatively cheap.

The tractor horsepower should be double the kilowatt output of the PTO generator. This is to accommodate various mechanical losses in the system and to have the tractor operating economically and the conversion between horsepower and kilowatts. For example, a 130 Hp tractor is the recommended motor size for a 63Kw PTO generator.

When operating a PTO generator the amps will vary as the rpm of PTO shafts vary. PTO speed needs to be managed so as not to overload the electrical installation. Consider a frequency-sensitive circuit breaker so that if the tractor’s rpm should increase or decrease then the electrical installation is protected.

Generator cut-over switches

You need to have the ability to connect the generator into your electrical installation and then to swap between sourcing electricity from it or from the network and to do so without compromising the safety and operation of the electrical installation. A backup generator is a heavy paperweight if a manual cut over switch is not installed.

Contact your electrician for advice on installing generators and your local generator supplier for advice on sizing and getting the right type of generator for your farm.

Alternatives for cooking and heating

How will you and other people on the farm cook when there is no power? A gas oven or barbecue to provide heating and hot water will be a major advantage in a power outage. A chip heater or fireplace can also be useful for warmth, hot water, drying clothes etc.

What to do

• Check that family and staff are safe and that they know there is a power cut.
• Check online if possible, to see if there is information about the cause of the outage and estimated restoration time.
• If your neighbour has power, the fault may be on your property - perhaps a fallen tree. A quick check for obvious problems before phoning the power company could pinpoint the location and save considerable time. Do not handle fallen cables.
• Always phone the power company, even if your neighbours have already phoned. The company may not realise that your power supply is out too. Also, if there is a widespread fault they will probably have an automated message telling you how long it will be before it is fixed.
• Communication with family and staff by two-way radio may be an option.