This article gives a description of electric motor capacitor test procedures to determine if a capacitor is damaged or working normally & test procedures to measure the capacitor's capacitance or microfarads, MFD, or uF to determine if it is working within its rated capacitance range.
In this comprehensive guide, we will delve deeper into the symptoms of a bad motor capacitor and explore the steps to address them effectively. One of the primary indicators of a defective motor capacitor is the motor's inability to start or a delayed start-up.
A start capacitor is only used in the motor circuit for a second or two when it first starts to turn. Once the motor is up to speed, the start capacitor disconnects and is not used again until the next time the motor starts. If the start capacitor fails, then the motor will not be able to begin turning.
When a capacitor is suspected of malfunctioning, performing electrical tests is essential for confirmation. Utilizing a multimeter with capacitance measurement capabilities, or a dedicated capacitance meter, technicians can compare the actual capacitance value to the rated specifications.
To test a capacitor, perform a capacitance test on the complete circuit. For applications with multiple capacitors with known capacitance ratings, such as the start winding of an integral hp/kW single-phase motor, compare the measured capacitance with the rated capacitance to verify the interconnection is correct.
Set the function switch on your multimeter to the Ohms function which may be indicated with an “Omega” (Ω) sign. Set the range switch to R X 1,000 or higher. Most VOMs have a 10,000 and 100,000 range and I prefer using the R X 10,000 range for testing motor capacitors. Touch the meters probes to the capacitor terminals.
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