Thanks Brandon; indeed one of the reasons I research and write is to learn by the process. To explain requires understanding.
Very true about the way electricity works. Movement of the electron, and we have never seen an electron, were just pretty dang sure it exists because we see the effects. I appreciate having this conversation with you. I certainly agree in principle. Years ago I sat in a room with six fellow electrical engineers and turned to one, Trudi Kappel who had a phD in the topic, and asked "So Trudi, how does electricity actually really work?
I appreciate that we certainly don't want to mislead or get folks in trouble on the topic. I appreciate your comments. That explanation you just made I feel is true enough without needing degree. The way electricity works is not up for debate simply because it may be harder to understand. I appreciate the argument for accuracy and clarity. When there's enough here I'll edit the article accordingly.
The danger is making it so correct as to confuse a non-electrician, right? Typically we do this by adding a second coil a coil is a wire round about an axis - a START COIL or "start winding" - that will create a magnetic field when energized to push the motor to get it started.
The starting capacitor "lags" the electrical current or puts it out of phase with the "run" current to the motor so that the two can work together to spin the motor. Typically these motors have a centrifugal switch a switch that will open when it's spun at sufficient speed that opens to take the start coil or aux coil out of the circuit once the motor is up to speed. Together those components are in essence giving the motor a "push" or as some writers say a "kick" to get it started.
That's the simplest design though not the most-efficient. A "fancier" design includes an aux coil that stays in operation as the motor is running, assisted by a "run" capacitor that requires and uses less power once the motor has started. So this design will have either two capacitors a bigger "start" cap and a smaller "run" cap or a single physical device that combines the two a "Start-Run" cap. Most writers simplify this a bit from the truth. Perhaps we need to make the article suit two audiences.
The angle between the stating winding and the running winding is almost 90 degrees. The magnetic field set up by the stator windings is almost identical to that of a two phase induction motor. Please read the excerpt, nothing about boosting here. Brandon The basic things we want read readers to understand here is 1.
We can recommend a couple of books whose explanation is easy to follow: Blume, Steven W. Electric power system basics for the nonelectrical professional. Rozanov, Yuriy, Sergey E. Ryvkin, Evgeny Chaplygin, and Pavel Voronin. Power electronics basics: operating principles, design, formulas, and applications.
CRC press, If you really want to know how electric motors work, buy a few textbooks on Amazon. On by mod - almost the entire explanation of how a start capacitor is wrong. It works by adding capacitive resistance to the circuit, that will alter the time the start winding is energized vs the run winding.
That difference in time between the start and run winding energization is what creates the rotating magnetic field. Need help with wiring the capacitor in on my 2hp bench grinder. It has a power switch, centrifugal switch, capacitor, two main windings, and a start winding.
Jim I'm answering beyond my expertise so this is just a guess: I think that up to a limit you can oversize a starting cap but if you go too far you simply burn up a seized motor or component.
Keep in mind that a starting cap may be simply giving a kick to a normally-operating motor, or it may be giving a big kick in the seat to an electrical motor in trouble, such as a hard-starting AC compressor. In the latter case, something is failing in the motor, maybe a bearing, and we're getting a bit more life by giving the hard-starting motor an extra push. But too big a push on a motor that's seized could cause something ugly to flare up.
So I think that on a 1 HP motor, either starting cap is in-range. If adding a hard start capacitor, SPP6 to an rv air conditioner enables it to start on a small watt generator sometimes would an SPP8E not give it even more help starting?
Could the SPP8e damage the compressor? Thank you. Indeed there are specialists H Shreck in Poughkeepsie used to be one of them who rebuild electric motors of all kinds. There are also many water pumps whose design makes it quite reasonable to replace pump impellers. The fan on my Conquest 80 will not stay on interior fan. It starts and then stops after a few seconds. It was installed in Often motors have two windings, a start winding and a run winding.
Your motor's run winding may be damaged. Or your fan motor may require a dual capacitor start and run or a separate run capacitor to keep it spinning.
We occasionally need to run off a generator w and we've found that the fan cause the generator overload to trip. The fan has been tested and observed to draw 8 amps running at full speed. Will need to confirm the motor size, just wondering if this would help. The total draw of all items is less than 20 amps and the generator is capable of supplying 25 amps constant. Joel I think the problem lies elsewhere and needs some further diagnostics. I suspect that your total current draw is exceeding the ability of the generator - you may be running more than the fan, such as lighting, a cooler, toasters, other electrical appliances.
If it were just the fan, drawing 8A, it has no business tripping the breaker. Put another way if the problem is the fan and there are NO other appliances running, then there is a failing fan motor drawing high current, or an electrical short circuit or other unsafe condition to find and fix.
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Apologies for the delay. Voltage sensing technology that monitors for motor start current sensing devices require internal fuse protection.
A 2-wire connection that simplifies installation 3. A secondary timing circuit that ensures that the capacitor is not permanently left in the start winding circuit 4. A fully electronic device - minimizing the limitations of mechanical devices and secondary fusing associated with triac devices 5.
Essentially, two plates are separated by a material known as a dielectric or insulator. These insulators can be mica, ceramic, porcelain, Mylar, Teflon, glass, or rubber.
Capacitors will also limit the current. They can be used to store voltage or build it up until the call for it to be released is present. A start capacitor is found in the circuit of start windings when the motor is starting. This capacitor contains a higher capacitance than a run capacitor. It varies, but a start capacitor will measure between 70 and micro Farads. The start capacitor provides an immediate electrical push to get the motor rotation started. Without a start capacitor when the voltage is applied, the motor would just hum.
The start capacitor creates a current to voltage lag in the separate start windings of the motor. The current builds up slowly, and the armature has an opportunity to begin rotating with the field of current. A run capacitor uses the charge in the dielectric to boost the current which provides power to the motor.
To ensure that the motor is operating at its highest efficiency, always use the dedicated capacitor that is included with the motor. The dedicated capacitor creates a 90 electrical phase shift from the auxiliary capacitor phase to the main phase.
Using the wrong capacitor can shift this away from the 90 degrees, and the resulting inefficiency can cause the motor to overheat with inconsistent torque or speed performance. Notice "Rated Speed" and "Rated Torque". This operating point where these two intersect on the curve is where the highest efficiency occurs. Every motor is designed for a rated load. This is why oversizing isn't the best way to size AC motors.
A difference in the capacitance in the capacitor will affect both rated speed and rated torque as the operating point shifts away from its maximum efficiency. If you use 2 of the same exact motors with vastly different capacitors, you will produce vastly different results. Once maximum efficiency is lost, heat generation increases for the motor. Excessive heat can degrade bearing grease and decrease long term life of the motor.
For a 3-wire AC motor, connect the red and white lead wires to opposite terminals of the capacitor. Connect the black lead wire to N neutral side of the power supply. For unidirectional operation, just wire the L live side of the power supply to the terminal closet to either the red lead wire clockwise or the white lead wire counterclockwise to start rotation. HINT: the 2 closest terminals are joined internally.
For bidirectional operation, use a single pole double throw SPDT switch in between the live wire and the capacitor terminals to switch direction. However, to switch direction of an induction motor, you must wait until the motor comes to a complete stop. For reversible motors, the direction can be switched instantaneously.
Now that you know the importance of capacitors, don't lose them. If you do, use the motor label to identify the right capacitor to use. Stay tuned for more troubleshooting tips. Topics: AC Motors. Oriental Motor offers an extensive product line-up of about 50, different products that provide the optimal motion system.
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