Farms only a few kilometres from town were stuck without power for days, causing stress and delay as owners arranged for generators to be begged, borrowed or shared to get milk out of cows. Even then problems arose with inadequate generation capacity to keep milk cool and to standard.
As the region’s dairy herds grow in size and number, power networks are under increased pressure to keep power flowing, but often nature works against them.
After the September storm Federated Farmers Dairy chairman Willy Leferink said any farmer with more than $2 million investment in dairy plant and herds must have “something wrong” if they could not spare an extra $10,000-$20,000 for a generator.
Graeme Church, director of Ashburton electrical contractor ElectraServe, estimates 90% of farms in the region are wired up for generators, but only about 60% would have one on hand.
“Of course when there is a storm everyone wants one at once, and they will struggle to get one either buying or hiring.”
The problem is complicated by there being no “one size fits all” for farm dairies, depending on the configuration and complexity of pumping, hot water and cooling systems.
Demand for generators since September has become so strong his company is about to start stocking them, and technicians are spending considerable time getting more dairies wired up.
Church has experience with the two main types of generators, PTO and self-powered, and sees positives and negatives in both.
The standard tractor PTO-driven generator will invariably be cheaper, and because it relies on a tractor it will be assured of running first time during a power outage.
“However, a disadvantage is that staff do not always set it up correctly, matching the PTO speed with the required generator speed.”
Too slow a PTO speed means the electrical motors will run slow and might not receive the correct voltage, resulting in them drawing more amps and possibly burning out. Running the PTO too fast will have motors working faster and harder than they should, also with the risk of damage.
“There is also the chance that if you are reliant on that tractor for other work, you will need it and can’t commit it to that job.”
He has one client who has two dairies and has opted to have a diesel generator on one and a PTO on the other “simply because he could not afford to have two tractors committed to generators”.
Diesel generators offer the obvious alternative, but their self-contained convenience means they can be subject to neglect between crises.
“They can tend to be left in a corner and forgotten about until they are needed.”
He cautions there are quality generators, and cheaper brands that might work, but only so well for so long.
Tracey Gordon, manager for ATS Energy in Ashburton, said interest was peaking in generator purchases. She said ATS retails two key brands, Powerbuilt and Condor, with proven background in industrial applications.
Church said it was important to “right size” the generator for dairy use.
“To get a motor started relies on considerably more energy than it uses to run. It’s hard to give a rule of thumb as every motor/starter combination and generator is different, however, a generator with output three times the amount of energy required by the motor it is powering is often required.”
A typical example could be a 2.2kW pump requiring a 6.5-7.5 kVA generator to get it successfully started.
“Matching one to one simply won’t be enough.”
Once running, careful management of the load on the generator is critical, and may involve some juggling of demand compared to the usual milking routine, reducing water pumping and heating of water cylinders for example.
A typical generator for many dairies would be in the 55-60kVA range. The industrial outlet Trade Tested sells a 50kVA generator for $17,999. Preserving power supply to farm houses can also be critical – many will have deep freezes with hundreds of dollars of food. Typically a 6.5 to 10kVA generator will cover domestic demands.
“You also don’t want to go to a generator that is too large,” he said.
“They need to work at a reasonable rate, doing too little work runs the risk they will oil up.”
Retro-wiring a dairy for a generator will typically cost $3000-$5000, and is obviously simpler when part of a new dairy wiring system.
Typically, any configuration will require a changeover switch and plug for connection.
“I cannot believe many sheds out there would not have the wiring and switch, but there are a few,” Church said.
“The payback period on a generator is relatively short, particularly when you allow for the reduced stress, peace of mind and animal health.”
Generators always at the ready
Tips for keeping generators "good to go".
• Keep them dry and warm. Any electrical component is allergic to moisture and cannot be expected to tolerate wet conditions and operate correctly, or safely
• Carry out one milking a month running on the generator. This will keep seals and engines lubricated, and importantly will ensure your staff know how to start and operate the generator, without damaging key components in the dairy.
• Protect generators from rodents. Rats in particular love wiring, and will scour off insulation easily.
• Regular checks. Make sure you check oil, water and fuel levels on diesel generators on a regular basis.
• An electrician’s check. Once every season or two, get an electrician to check the electrical connections inside the generator, as excessive vibration over time can cause connections to become loose, which causes overheating of the terminations leading to eventual failure
Reliability ranks highest
Rakaia farmer Dave Letham has a cautionary tale for anyone considering picking up a “too good to be true” deal on a farm generator.
From his experience, if it looks that way, then it probably is.
Like many dairy farmers throughout mid-Canterbury his 1200-cow operation was struck by power outages in September last year.
“We had an imported generator that was only five years old and had only done 32 hours, and a lot of that was just keeping it warmed up over winter and maintenance runs.
“We had it doing a day’s work over the September storm, and it died with 60 cows on the platform. The guy who sold it to us would not answer his phone. I took it up to them asking for it to be fixed. It only went for a day and a half doing what we put it in to do, supply power to milk the cows.”
Now he has installed a highly reputable Caterpillar brand generator, valued at about $30,000. This compares with about $18,000 paid for the 100kVA generator that let them down.
“We figure that at certain times of the year you simply do not want the cows’ lactation to be interrupted, and September is certainly one of them when you are trying to get them building to a peak, you don’t want that check coming from being unable to milk them.”
The higher purchase price of the Cat generator reflects the level of service behind it, with three technicians in Canterbury on call 24/7 should problems arise.
Graeme Church, director of Ashburton based electrical contractors Electraserve, said there were a number of Chinese-sourced generators being sold, with farmers reporting problems with them.
Letham’s neighbour also had a dubious generator that gave out after only a couple of hours of operation.
In the months after the storm dairy farmers who have not had a generator are now working to get them installed. He knows of one reputable agri-retail outlet that has bought in generators of less than reliable standard. For farmers converting to dairying, the need to watch their spending might be why less than sound generators have been installed.
Letham believes self -powered generators will always be the better option.
“If it’s snow that’s caused the outage, then you can be pretty sure you will be needing the tractor to feed out, so a PTO-driven generator is probably not ideal.”
After the last storm he doubts there would be many dairy farmers without a generator, or access to one.
