How do you calculate the speed of the motor?

Question

How do you calculate the speed of a dc motor or a solar motor? Like could anyone give me the formula or a website of how to calculate the speed of a dc or solar motor?

Answer 1

it sounds way to complicated, since varying the voltage and current and frequency to the motor results in different speeds, and of course there is a limit at which will burn it out. RPM means revolution per minute. RPM's is the standard measurement. It would make more sense to add a speed sensor to figure it out. There are different ways to do that. You could use an optical sensor, or a contact that can be read by a frequency meter, such as can be found on cheapo digital volt meters. Another novel way would be to use a signal generator and a small audio transformer to step up the voltage from the generator to about 100 volts, then connect a neon bulb to it. If it lights up, you have succeeded in hooking it up ok. Neon bulb are like the ones on electric blankets for your bed. Then place a felt marker mark on the shaft of the motor, then start the motor, then turn on the generator. Adjust the generator while holding the neon bulb near the motor shaft. (with lights in house off so you can see the bulb and mark ok) when the mark on the shaft appears to stop moving, read the frequency on the generator, multiply it by 60 and presto, you have the rpms. If the frequency says 1000Hz (or 1kHz) then 1000 x 60 = 6000 rpm. Why because Hz equals how many times per second and then multiply 60 because there are 60 seconds in a minute. You might even come close using a neon bulb guitar tuner if you raise and lower the motor voltage until it appears to stop motion.
If you dont have any access to these items then borrow a meter from someone. make a device that acts like a switch everytime it turns once. Then hook up the meter set to Hz and measure. Dont forget to add a 1.5 battery in series to the meter or else it might not read it due to the signal being too small from the switch alone. Also you will have to convert the reading from the meter here as well. Hope it helps you
By the way I suggest you do not in any way try using the power socket in your house, it is very dangerous. I propose you use the switch method and meter.

Answer 2

The speed of an AC motor is determined by the Hz of the electric supply and the poles of the motor. This is not the case in DC. Generally, DC motors simply go faster with more voltage. If you cut the DC voltage in half, the current will also drop in half, giving you only 1/4 of the motors normal power. What this will do to the speed depends on the load. At 1/4 power, the motor may not turn at all while under load. The best way to control the speed would be with a PWM controller.

Answer 3

Usually you "measure" the speed of a motor. But in a pinch, you can measure the voltage across a DC motor and if you know the motor constant (that might be present in the motor literature; it depends on the motor design) you can calculate the speed as something like Voltage / Motor constant. It won't be super accurate, but it will be close enough for many purposes.

Answer 4

the speed of a dc motor depends on the design of the motor

the "formula" is different for different motors

typically a DC motor is designed to run its maximum speed at its rated voltage, perhaps 2000 rpm at 90V DC

if you have that design information, you can assume the turndown is linear (that will be close) in other words at 45V the motor above would run at 1000 rpm

it depends on your motor, they are designed differently for different applications, loads, etc

Answer 5

Purchase a techometer and directly find the speed on the meter

Answer 6

Not sure but there is an author named Chapman, Stephen J. that writes great books on that stuff.

Answer 7

speed of dc depends much on applied voltage,if we reduce half of its total voltage,speed will too decrese to its half

Answer 8

Isn't everything in rpm's as for speed.

Answer 9

The best method would be a strobe tachometer - any other method would be approximate at best.