USA-Generator

Generator Load Charts

Basic Standby Power Requirements

To design a standby emergency power system for your home or farm, begin by tabulating all of the loads that may operate at one time. The best way is to record the actual loads from nameplates of the electrical equipment directly . If this is not possible, the tables and charts at the end of this chapter will provide a reasonable estimate of loads of the various machines on farms.

When sizing loads for motors on the farm, both the running load and the start up load must be considered. Table 2 lists typical loads for a range of motor horsepower. The start up load may be much higher than listed if the motor must typically start under load. For example, a start up load of 4 times running load may be reasonably accurate if the silo unloader is raised off the surface of the silage but, if it must start when buried in the frozen silage face, the load could be 12 to 20 times normal running load. A good management technique is to minimize the situations where motors need to start under load.

The pie charts were developed from a survey of 177 livestock farms in eastern Ontario. They depict averages and therefore should only be used as a general reference in estimating your farm conditions. The graphs show several things. First of all, the total average electrical load is shown and varies by both farm type and farm size. Secondly, the charts portray the portion of that load that is demanded by each part of the farm operation. For instance, the utility load, which is primarily the farmhouse, averages about 11 kW for all of farms. However, on a percentage basis, it is 76% of the load on sheep farms but only 15% on layer farms because the difference in total demand load.

It is important to also realize that load does not equate to usage. Tables 3 through 8 give an indication of annual consumption of electricity by various farming operations. Consumption is the combination of load and duration. The demand load (kW) is important in determining the size of the emergency generator. Consumption (kWh) is important from the standpoint of energy management and only comes into play in designing the emergency power supply when time of use is a factor. Use Tables 3 -8 to compare power use among various types of loads. For example, in Table 3, a direct expansion bulk tank milk cooler with a heat exchanger uses about 82 kWh of electricity per cow per year as compared to the same unit, without a heat exchanger, uses about 154 kWh per cow per year. Therefore, one way to save energy is to install a unit with a heat exchanger.

To illustrate demand load, a farming operation contains of a number of electrical loads. If none of these loads were ever operated together, the generator size would be based on the largest load only. However, there are two constraints on that design. Firstly, there may not be enough hours in the day to perform each operation in sequence. Secondly, it is typical that a number of loads must operate at the same time in order to accomplish a task. Feeding, for example, may require that a silo unloader, a feed mixer, and a feed conveyor, all operate at once. At the same time, some lights may be on and ventilation fans may be operating. Therefore, the generator size must be based on the sum of all the loads that must operate at one time. If some of those loads are motors then the start up load of the largest motor must also be included. The next consideration is the loads you want to operate at the same time. For instance, you may want to perform both milking and feeding, at the same time, for the sake of convenience or time management. Of course, the ultimate scenario is where all of the farm operations may occur together, as would happen with grid power. Farms that have automatic standby systems will have generators sized for that condition. Most farms will choose an option somewhere between the extremes, based on the specific demands and constraints of that farm. Chapter 3 provides a template that can be used to consider the best options for your farming operation.

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Table 1: Typical Equipment Wattage (Farm Equipment)

Farm Equipment	Typical Wattage
Bulk Milk Cooler	1500-12,000
Electric Fencer	7-10
Feed Conveyor	800-5,000
Feed Grinder	1,000-7,500
Feed Mixing	800-1,500
Gutter Cleaner	3,000-5,000
Infrared Lamp	250
Milking Machine Vacuum Pump	800-5,000
Milking Parlour Heater	2,000-10,000
Shop Tools	300-1,500
Silo Unloader	2,000-7,500
Space Heater	1,000-5,000
Ventilation Fans	300-800
Water Heater	1,000-10,000
Water Pump	500-2,500
Yard Light	100-500

 

Table 1: Typical Equipment Wattage (Essential Home Equipment)

Essential Home Equipment	Typical Wattage
Electric Heater	600 & up
Freezer	600-1,000
Furnace Blower	400-600
Furnace Oil Burner	300
Furnace Stoker	400
Refrigerator	400-800

 

Table 1: Typical Equipment Wattage (Optional Home Equipment)

Optional Home Equipment	Typical Wattage
Central Air Conditioner	2,000-5,000
Coffee maker	1,000-1,500
Dishwasher	300 + 1,500 for heater
Electric Clothes Dryer	500 + 4,000 for heater
Electric Fan	75-300
Electric Iron	500-1,500
Electric Range	3,000-4,000
Electric Skillet	1,150-1,500
Kitchen Ventilator	150
Mixer	150
Sewing Machine	200-500
Sweeper	400-1,500
Television	200-500
Toaster	1,200-1,500
Washing Machine	400
Water Heater	1,000-5,000
Water Pump	800-2,500
Window Air Conditioner	1,000-2,500

 

Table 2: Motor Wattage - Starting and Full-load Running Wattage Required for Single Phase Electric Motors

Motor Horsepower	Watts Required
	To Start	To Run
1/4	1000	215
1/4	1500	300
1/3	2000	400
1/2	2300	575
3/4	3345	835
1	4000	1000
1.5	6000	1500
2	8000	2000
3	12,000	3000
6	18,000	4500
7.5	28,000	7000
10	36,000	9000

 

(A) Task or operation	(B) Loads or area involved	(C) Electricity used (kWh/year per cow)
Milk cow preparation	Washers with sprinkler boosters	18.4 to 19.6
Milking system (by type)	Bucket milker	35
	Bucket milker and transfer	80
	Parlor – pipeline	110
	Can cooler	160
	Direct expansion bulk tank with precooler	95
	Direct expansion bulk tank without precooler	143
	Direct expansion bulk tank with heat exchanger	82
	Direct expansion bulk tank without heat exchanger	154
Ice bank cooler	without heat exchangers	182 to 222
Milking operation	Vacuum pump	74 to 76
Water heating	Fast recovery without heat exchangers	170
	Fast recovery with heat exchangers	151
Feeding	Silo unloaders	26
	Silo unload and silage feeding (system)	44.5
	Above unload, feeding plus hammer mill	67
	Grain grinding/ feed mixing, auto	6.5 to 8.2
Water supplies	Well pump	18
	Livestock watering (outside)	5 to 7
	Livestock watering (inside)	4
Manure handling	Gutter cleaner	12
	Liquid waste	26.3
Space conditioning (lighting)	Lighting for milking operations	48.5
Space conditioning (ventilation)	Milk parlor and milk room	10 to 20

(A) Task or operation	(B) Loads or area involved	(C) Electricity Used
Breeding house	Air conditioning 3.6-t (4-ton) unit	150 to 220 kWh per sow
	Fan ventilation with foggers	13.5 kWh per sow
Farrowing house	Air conditioning 3.6-t (4 ton) unit	93 kWh per sow
	Fan ventilation	41 to 47 kWh per sow-litter
Brooding	Cable, in-floor	50 to 100 kWh per sow-litter
	400 W per pen
	Cable, in-floor 300 W per pen	19 kWh per sow-litter
	Commercial pads 300 W per pen	40 to 120 kWh per sow-litter
	Heat lamps 250 W per pen	6 kWh/day per sow-litter
Nursery building	All uses	16.8 kWh per pig housed
Finishing operation	Ventilation of confinement house	10.4 kWh per hog marketed
	Feed augers and lights	0.3 kWh per hog marketed
Watering	Outside location	5 to 10 kWh per hog marketed
	Inside location	2 to 3 kWh per hog marketed
	Pumping/distribution	3 kWh per hog marketed
Feed handling	Grinding/mixing	2.2 kWh per hog marketed

 

(A) Task or operation	(B) Loads or area involved	(C) Electricity used (kWh/year per 100 birds)
Production lighting	Controlled incandescent lamps	64
	Controlled light in windowless house	328
	Controlled light in solar house	101
	Controlled light in conventional house	42
Ventilation	Fan size and number unknown	150
Water heating	One heater	9
Feeding	Auto-feeders	25.6
Egg collection	Automatic unit	17.3
Egg processing	Automatic unit	29.2
Egg washer	Automatic unit	21.4

 

(A) Task or operation	(B) Loads or area involved	C) Electricity used (kWh/year per 100 birds)
Brooding broilers	1560-W hover units	18 to 44
Whole-house brooding unit	Quartz heat brooders	34.3
	Space heaters (supplemental)	5.0
	Lighting	7.0
	Ventilation	13.5
	Feeders	0.9

 

(A) Task or operation	(B) Primary loads		(C) Electricity used
	(kW)	(hp)
Feed grinding (hammer mill)	2.24	3 (15% corn)	1.8 to 2.7 kWh/t
	2.24	3 (25% corn)	2.4 to 12 kWh/t
	2.24	3 (dry oats)	1.9 to 22 kWh/t
	2.24	3	1.5 to 5.5 kWh/t
Auto feed grinding systems (mill motor)	7.5	10	9.43 kWh/year per cow
			2.13 kWh/year per hog
			2.02 kWh/year per bird

 

This information is provided as a public service, but we cannot guarantee that the information is current or accurate.
Readers should verify the information before acting on it. This information provided and maintained by the Government of Ontario, Canada