Question: with the recent storm damage and our electricity supply being out for close to a week, I want to ready myself for further incidents and purchase a generator. I am milking 100 cows (winter milking) with the bulk tank, plate cooler, parlour and scrapers all requiring power. What should I go for regarding size, and should I go for a PTO generator or a diesel/petrol one?
Answer: we have had multiple enquiries similar to this, and speaking to some milking machine technicians, it is on the mind of nearly any dairy farmer, as they are most affected by power outages due to the needs listed in the above question. For drystock farmers, it is often a case of not having yard or shed lights, or for those who are not on a group water scheme – a functioning water pump.
When it comes to any type of generator, a standby switch is required to allow the generator to feed only the dwelling house or farmyard. Where this is not in place, there is a risk of power going back the main line and could be potentially dangerous to crews working to restore power. The changeover switch will be wired into the meter, and often this is where the input lead will be located to plug in to a diesel or petrol generator. This type of work should only be completed by a registered electrician.
PTO generators
There are two types of generators most farmers choose from. The most common type on dairy farms is a PTO-powered generator. This is connected to the tractor’s PTO output and the PTO, with a tractor with a 1,000-rpm speed box required to power it.
This will require a tractor available to use for this purpose. Where there is just one tractor on the farm that is required for several hours of feeding, this may be an issue regarding milk cooling.
PTO-powered generators are available under TAMS in the Dairy Equipment Scheme and carry a reference cost of €121.12 per KW. As it is classed as a fixed item in TAMS, full approval will be required before laying down a deposit or the full price.
PTO generators can be fixed to the ground or can be fitted to a three-point linkage and shared between a dwelling house or other neighbouring farmers, but should you receive a TAMS inspection, it would be expected that the generator is fixed in place in your yard.
Diesel or petrol generators
Diesel or petrol generators are a less common option for farmers, as the cost for a unit that is sufficiently capable of supplying their power needs is often too high for the frequency they are used. There is no TAMS aid available for either, regardless of you being a dairy or drystock farmer.
The benefit of a large diesel generator is that they can be fitted with a standby switch, which will kick in automatically should the mains power be cut. Thinking again of milk cooling, this could prove very valuable to farmers with large volumes of milk in the tank.
Cost wise, it’s important to remember that you are buying a diesel engine that is likely similar in size to a small tractor, so it will never be as competitively priced as a PTO-powered generator. Most farms will see themselves footing a bill of €10,000-€15,000 for a suitable-sized diesel generator.
Power requirement
My colleague Aidan Brennan looked at this issue back in our winter-ready focus in 2022. Aidan advised medium-sized dairy farms should have sufficient power in 33kVA generator, which should comfortably power the milking parlour, bulk tank and scrapers, etc. Bradley Generators say as a rule of thumb, parlours less than 10 units require a 27kVa generator, with 10-18 units requiring a 33kVa, with larger parlours needing a 40kVa. A 33kVA single-phase generator rated at 144 amps will cost approximately €4,300 plus VAT, much the same price as a 50kVA three-phase rated at 72 amps. Under TAMS reference costs, this 33kVA generator has only a costing of just under €3,200.
However, a 72 amp supply is unlikely to be sufficient if a number of large items are needed to run at the one time, such as the vacuum pump, milk cooling unit and scrapers. For example, a vacuum pump for a 16-unit parlour will require 26 amps, the bulk tank will require 30 amps and water heaters may require 26 amps. That’s the load exceeded already before lights or scrapers are turned on. It’s important to consult your electrician who works on your milking machine as to power requirements and then purchase above the minimum.
For power requirement of the tractor running them, for single phase generators, Bradley Generators recommended multiplying the kVA by 2.25 to get the required horsepower in our 2022 article. In this case, a 33kVA generator will require a 75hp tractor.They also recommend running the generator several times a year.
Diesel-powered generators will likely be a five-figure sum for a new unit, but come with the benefit of being able to be wired to kick in automatically should mains power be cut.
Question: with the recent storm damage and our electricity supply being out for close to a week, I want to ready myself for further incidents and purchase a generator. I am milking 100 cows (winter milking) with the bulk tank, plate cooler, parlour and scrapers all requiring power. What should I go for regarding size, and should I go for a PTO generator or a diesel/petrol one?
Answer: we have had multiple enquiries similar to this, and speaking to some milking machine technicians, it is on the mind of nearly any dairy farmer, as they are most affected by power outages due to the needs listed in the above question. For drystock farmers, it is often a case of not having yard or shed lights, or for those who are not on a group water scheme – a functioning water pump.
When it comes to any type of generator, a standby switch is required to allow the generator to feed only the dwelling house or farmyard. Where this is not in place, there is a risk of power going back the main line and could be potentially dangerous to crews working to restore power. The changeover switch will be wired into the meter, and often this is where the input lead will be located to plug in to a diesel or petrol generator. This type of work should only be completed by a registered electrician.
PTO generators
There are two types of generators most farmers choose from. The most common type on dairy farms is a PTO-powered generator. This is connected to the tractor’s PTO output and the PTO, with a tractor with a 1,000-rpm speed box required to power it.
This will require a tractor available to use for this purpose. Where there is just one tractor on the farm that is required for several hours of feeding, this may be an issue regarding milk cooling.
PTO-powered generators are available under TAMS in the Dairy Equipment Scheme and carry a reference cost of €121.12 per KW. As it is classed as a fixed item in TAMS, full approval will be required before laying down a deposit or the full price.
PTO generators can be fixed to the ground or can be fitted to a three-point linkage and shared between a dwelling house or other neighbouring farmers, but should you receive a TAMS inspection, it would be expected that the generator is fixed in place in your yard.
Diesel or petrol generators
Diesel or petrol generators are a less common option for farmers, as the cost for a unit that is sufficiently capable of supplying their power needs is often too high for the frequency they are used. There is no TAMS aid available for either, regardless of you being a dairy or drystock farmer.
The benefit of a large diesel generator is that they can be fitted with a standby switch, which will kick in automatically should the mains power be cut. Thinking again of milk cooling, this could prove very valuable to farmers with large volumes of milk in the tank.
Cost wise, it’s important to remember that you are buying a diesel engine that is likely similar in size to a small tractor, so it will never be as competitively priced as a PTO-powered generator. Most farms will see themselves footing a bill of €10,000-€15,000 for a suitable-sized diesel generator.
Power requirement
My colleague Aidan Brennan looked at this issue back in our winter-ready focus in 2022. Aidan advised medium-sized dairy farms should have sufficient power in 33kVA generator, which should comfortably power the milking parlour, bulk tank and scrapers, etc. Bradley Generators say as a rule of thumb, parlours less than 10 units require a 27kVa generator, with 10-18 units requiring a 33kVa, with larger parlours needing a 40kVa. A 33kVA single-phase generator rated at 144 amps will cost approximately €4,300 plus VAT, much the same price as a 50kVA three-phase rated at 72 amps. Under TAMS reference costs, this 33kVA generator has only a costing of just under €3,200.
However, a 72 amp supply is unlikely to be sufficient if a number of large items are needed to run at the one time, such as the vacuum pump, milk cooling unit and scrapers. For example, a vacuum pump for a 16-unit parlour will require 26 amps, the bulk tank will require 30 amps and water heaters may require 26 amps. That’s the load exceeded already before lights or scrapers are turned on. It’s important to consult your electrician who works on your milking machine as to power requirements and then purchase above the minimum.
For power requirement of the tractor running them, for single phase generators, Bradley Generators recommended multiplying the kVA by 2.25 to get the required horsepower in our 2022 article. In this case, a 33kVA generator will require a 75hp tractor.They also recommend running the generator several times a year.
Diesel-powered generators will likely be a five-figure sum for a new unit, but come with the benefit of being able to be wired to kick in automatically should mains power be cut.
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