![]() ![]() The metal housing is fabricated to fit tightly around the capacitor and hold it in place. Physical size is important because the capacitor must fit inside the compartment attached to the motor.Oftentimes this temperature isn’t reported on the label. Operating at or above this temperature can de-rate the life of the capacitor. Operating temperature is the maximum operating temperature at which the capacitor is designed to run.However, many capacitors can operate using either frequency. It can be either 60 hertz (Hz) (US) or 50 Hz (Europe and South America). Electrical frequency is the frequency of the power coming into the motor.Voltages vary depending upon use (start or run capacitor). Voltage rating is based on the peak voltage (V) the capacitor will experience during operation.Capacitors must be replaced with similar capacitance μF ratings. Capacitance is the amount of stored charge in the unit and is typically measured in microfarads (μF) for motor capacitors.The label contains important information including the capacitance range (460 to 552 μF), voltage rating (125 V), and electrical frequency (50 or 60 Hz). You can keep track of this information using the motor capacitor evaluation worksheet in “NPTC Tools of the Trade: Testing a Motor Capacitor,” (Extension publication ANR-2783).įigure 4. The parameters are capacitance, voltage rating, electrical frequency, operating temperature, and physical size. Motor capacitors are specified using five parameters, with four typically listed on a label (figure 4). (You should get a low-pressure alarm for this.) You will be paying for four times the electricity in this motor and losing bird performance with reduced air exchange. If this fan is on for a short amount of time (30 seconds), it will never move air before the timer shuts off. If the capacitor is getting weak, the fan may get up to speed, but it draws higher current for a longer period. This fan will continue to do this until the motor overheats and trips a thermal switch. ![]() The fan with a dead start capacitor immediately begins and continues to draw 27.3 amps while the fan hums and grinds and never begins to rotate. The fan with a working start capacitor uses a short spike in current draw (27.2 amps at 120 volts) to spin the fan up quickly and then drop to an operating current of 6.1 amps. ![]() Graph of current draw from a 1⁄2 hp fan motor (wired for 120 volts) using working, weak, and dead capacitors over a 60-second period.įigure 3 is a graph of current draw from the 1⁄2 hp fan motor over a 1-minute period using working, dead, and weak start capacitors. This shows the value of a start capacitor and why producers should care that it is working.įigure 3. A switch on the start capacitor allows us to demonstrate a “working” capacitor and a “dead” capacitor. A motor capacitor is an electrical storage unit that stores and releases energy to increase the current to one or more copper windings of a single-phase motor to create this extra boost and increase the motor torque.įigure 2 shows a 36-inch galvanized fan with cone that we use to demonstrate motor capacitors at the National Poultry Technology Center (NPTC). Single-phase alternating current (AC) motors are designed to carry a given load but need an extra boost to get and sometimes keep the load moving. The fan has a 1⁄2 hp motor with a switch on the start capacitor to demonstrate a “working” capacitor and a “dead” capacitor. A 36-inch galvanized fan with cone demonstration unit. A broiler producer replacing a 1 horsepower (hp) electric motor on a tunnel ventilation fanįigure 2. A capacitor can be checked and replaced in 20 minutes if the producer has the replacement on hand, a few tools, and the knowledge to safely troubleshoot.įigure 1. Motor capacitors cost between $10 and $20 depending on the capacitor use, size, and brand name. Oftentimes it is not the motor that has gone bad but a motor capacitor that has failed. The motor can take 1 to 2 hours to replace depending on how easy it is to remove attached equipment, such as pulleys and shafts, and rewire and attach the new motor. The cost of replacing a farm motor can range between $200 and $500-plus depending on the type of motor, size, and brand name. We see and hear of the challenges producers face in swapping out electric motors (figure 1) when they “go bad” and stop working. A two-house (66 × 600 feet each) poultry farm, for example, has over 80 electric motors comprised of 48 fan motors, 16 feed line auger motors, 4 feed fill auger motors, 4 tunnel door/curtain machine motors, 4 vent machine motors, and others. They drive ventilation fans, heater blowers, stir fans, feed bin and feed line augers, lift systems for feed and water lines, and actuators for tunnel and vent doors. Electrical motors are an integral part of a poultry farm operation. ![]()
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