First, let me say I know just enough about electricity to be dangerous. I am a retired diesel tech that has been forced back into "making ends meet" due to inflation. I have a strong background in automotive electronics but am a bit weak when it comes to alternating current. Much of my current work involves ac motors and I try to read all I can to keep myself safe and to not screw up the customer's equipment.
I recently had a job repairing an automatic gate opener for a client's storage yard. The electric motor that ran the gate would not start. I removed the motor and used the capacitor test function on my Fluke 87a multimeter to determine that the capacitor attached to the motor was open. And, here's where I ran into a problem that I'm hoping someone on this forum might be able to explain.
The capacitor was labeled 65 microfarad +/- 5%, 240vac. Ok, I'll just run down to the air conditioner supply I do business with and buy another. NOT! This capacitor is not available anywhere that I can find including the OEM of the gate controller. All info that I read on motor capacitors also leaves me confused.
Start capacitors are typically rated at 125, 165, 250 and 330 volts while run capacitors are typically 370 and 440 volts. So, my cap's voltage is in the start column.
But, start capacitors usually have a wide spread or range of capacitance like 65-77 mfd while run caps are very specifically rated with a tolerance usually given as 5 or 6%. So, that puts my cap in the run category.
Of course, silly me, I want to know why. No one locally, including severaly motor repair shops and even the controller manufacturer themselves seem to be able to answer my question as to what this capacitor is actually called and why it is so different from most other applications I have come across. The gate control people said to call it a run capacitor and that they can't get it anymore so they use one that is 60mfd and 250 volt instead. That is what they sold me and it works but I would like to know more.
Any input appreciated and thanks for reading.
I recently had a job repairing an automatic gate opener for a client's storage yard. The electric motor that ran the gate would not start. I removed the motor and used the capacitor test function on my Fluke 87a multimeter to determine that the capacitor attached to the motor was open. And, here's where I ran into a problem that I'm hoping someone on this forum might be able to explain.
The capacitor was labeled 65 microfarad +/- 5%, 240vac. Ok, I'll just run down to the air conditioner supply I do business with and buy another. NOT! This capacitor is not available anywhere that I can find including the OEM of the gate controller. All info that I read on motor capacitors also leaves me confused.
Start capacitors are typically rated at 125, 165, 250 and 330 volts while run capacitors are typically 370 and 440 volts. So, my cap's voltage is in the start column.
But, start capacitors usually have a wide spread or range of capacitance like 65-77 mfd while run caps are very specifically rated with a tolerance usually given as 5 or 6%. So, that puts my cap in the run category.
Of course, silly me, I want to know why. No one locally, including severaly motor repair shops and even the controller manufacturer themselves seem to be able to answer my question as to what this capacitor is actually called and why it is so different from most other applications I have come across. The gate control people said to call it a run capacitor and that they can't get it anymore so they use one that is 60mfd and 250 volt instead. That is what they sold me and it works but I would like to know more.
Any input appreciated and thanks for reading.