- Industry: Electrical equipment
- Number of terms: 4774
- Number of blossaries: 0
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Motor which employs a main winding and an auxiliary winding, which is called the starting winding. The windings are unlike and thereby "split" the single phase of the power supply by causing a phase displacement between the currents of the two windings thus producing a rotating field. After the motor has attained approximately 75% of rated speed, the starting winding is automatically disconnected by means of a centrifugal switch or by a relay. The motor then continues to run on a single oscillating field, which in conjunction with the rotation of the rotor, results in a rotating field effect. Since there is no rotating field, after the starting winding is de-energized, the rotation cannot be changed until the motor has come to rest or at least slowed down to the speed at which the automatic switch closes. Special starting switches are available as well as special reversing switches which have a means for shunting the open contacts of the automatic switch while the motor is running and thus permits the split phase motor to be reversed while rotating. This type of starting is found typically on single phase fractional motors.
Industry:Electrical equipment
The speed of the motor refers to the RPM's (revolutions per minute) of the shaft.
Industry:Electrical equipment
A stabilised shunt-wound motor is a direct-current motor in which the shunt field circuit is connected either in parallel with the armature circuit or to a separate source of excitation voltage and which also has a light series winding added to prevent a rise in speed or to obtain a slight reduction in speed with increase in load.
Industry:Electrical equipment
Amount of current drawn at the instant a motor is energised - in most cases much higher than that required for running. Same as locked rotor current.
Industry:Electrical equipment
The torque or twisting force delivered by a motor at the instant it is energized. Starting torque is often higher than rated running or full load torque.
Industry:Electrical equipment
That part of an AC induction motor's magnetic structure which does not rotate. It usually contains the primary winding. The stator is made up of laminations with a large hole in the centre in which the rotor can turn; there are slots in the stator in which the windings for the coils are inserted.
Industry:Electrical equipment
A physical protection placed over the external connexions point on medium and high voltage motor leads. Stress cones are used to avoid di-electric breakdown of motor leads in the vicinity of the external connection. Stress cones generally require an oversized conduit box on large motors.
Industry:Electrical equipment
Letter suffixes sometimes follow the NEMA frame size. Some of these suffixes, according to NEMA standards, have the following meanings
Industry:Electrical equipment
A capacitor device usually mounted in the conduit box to flatten the voltage surges that may occur as a result of lighting or a power supply surge (short-period peak). These surges could result in more than twice the rated voltage going to the windings and in turn cause winding damage.
Industry:Electrical equipment
A motor which operates at a constant speed up to full load. The rotor speed is equal to the speed of the rotating magnetic field of the stator; there is no slip. There are two (2) major types reluctance and permanent magnet on synchronous motors. A synchronous motor is often used where the exact speed of a motor must be maintained.
Industry:Electrical equipment
