Exactly.
Motor slip
- Thread starter domnic
- Start date
- Status
Exactly.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Actually, the discussion, being that it would pertain to his question about SLIP, should preclude discussing synchronous motors at all. "Slip" ONLY pertains to asynchronous motors, so essentially the OP had delineated the discussion from the outset. That however didn't stop it from heading off into the weeds.
An induction motor CANNOT run at synchronous speed. There was no point in bringing it up. The word "synchronous" was originally brought into this as part of the discussion about what the definition of slip is. It's as if someone were describing the color orange by saying that it is a combination of yellow and red, then people started talking about red things. Not germane to the original issue. Let's all drop it now before the thread has to be closed due to acrimony.
mivey
Senior Member
No worries mate. I understand the point you were making. I was just trying to convey why your point may have been missed.
I miss-read it when I first read it and just assumed it was a typo because I know what you were driving at did not match how I read it.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
Okay, so to summarize for the OP after all of the discussion:
'Slip' is a description of the speed of an induction motor in operation. Induction motors are sometimes called 'asynchronous' motors.
Induction motors are among the most common industrial motors, but there are other types; slip only applies to some types of motor.
Induction motors have stator windings which produce a rotating magnetic field. The speed of this rotating field is called 'synchronous speed'. In order to produce torque, the rotor of an induction motor must spin at a different speed than synchronous speed.
If the rotor is spinning at synchronous speed, slip is _0_ and no torque is produced. A completely unloaded motor can spin very close to synchronous speed, but there will always be just a bit of slip, to produce enough torque to overcome friction.
If the rotor is locked, then slip is defined as 1.
Common induction motors will have full load slips somewhere in the 0.01 to 0.05 range, or 1-5%, but greater slip is certainly possible for some systems.
Motors can operate with negative slip, meaning that the rotor speed is greater than synchronous speed. In this case the machine is actually operating as a generator.
Slip greater than 1 is possible, and may be used in some systems for rapid braking.
Some types of motor operate _at_ synchronous speed. These are commonly called 'synchronous' motors, and produce torque using a different rotor magnetic field.
-Jon
'Slip' is a description of the speed of an induction motor in operation. Induction motors are sometimes called 'asynchronous' motors.
Induction motors are among the most common industrial motors, but there are other types; slip only applies to some types of motor.
Induction motors have stator windings which produce a rotating magnetic field. The speed of this rotating field is called 'synchronous speed'. In order to produce torque, the rotor of an induction motor must spin at a different speed than synchronous speed.
If the rotor is spinning at synchronous speed, slip is _0_ and no torque is produced. A completely unloaded motor can spin very close to synchronous speed, but there will always be just a bit of slip, to produce enough torque to overcome friction.
If the rotor is locked, then slip is defined as 1.
Common induction motors will have full load slips somewhere in the 0.01 to 0.05 range, or 1-5%, but greater slip is certainly possible for some systems.
Motors can operate with negative slip, meaning that the rotor speed is greater than synchronous speed. In this case the machine is actually operating as a generator.
Slip greater than 1 is possible, and may be used in some systems for rapid braking.
Some types of motor operate _at_ synchronous speed. These are commonly called 'synchronous' motors, and produce torque using a different rotor magnetic field.
-Jon
kwired
Electron manager
- Location
- NE Nebraska
The synchronous motor has current injected into the rotor making it a different animal then when rotor current is only induced into it.
You could have a high inertia type of load that at times is feeding energy back to the motor, and could be running at, near, or even beyond synchronous speed. Closer you get to synchronous speed the less torque the motor is putting out, at sync speed there is no torque, beyond sync speed the motor becomes a generator.
- Location
- Massachusetts
At the least start with that before going to deep.
- Status