Sunner India :
M/s Renowned Engineers Private Limited is a successful organisation run by efficient and expert professionals.Sunner India Flexible Shaft Machines have stood the test of time both in quality and performance in our country and devolping nations too; to name a few destinations » SOUTH EAST ASIAN COUNTRIES - Dubai, Yemen,Oman,Saudi Arabia » AFRICA - Kenya, Sudan, Egypt, Libya, Nigeria, Zambia » RUSSIA - Uzbekistan,Turkmeinstan,Kazakhstan » NEIGHBOURING COUNTRIES - Myannamar,Nepal,Pakistan,Sri Lanka,Afghanistan and Bangladesh In short, 1 million satisfied customers throughout the globe has bench marked their quality standard and perfection too of every single product churned out from their works. In our pursuit to excellence we in our team have opted to categorically serve the global market with our existing technology i.e., rotor and stator to the power tool market too. The process is on and it is charged, it would be customer delight from now on. We manufacture SUNNER INDIA FLEXIBLE SHAFT MACHINES rangng from 0.75 to 2.5 H.P. and also with single phase and three-phase range.
Our motors are
thoroughly tested for insulation and overloading;
incorporated with a high quality windings and
bearings. The motors are absolutely trouble free
and mounted with an easily accessible rotary switch.
Our flexible
shafts are manufactured with superior quality raw
material to ensure longer product life. The shafts
can be easily fitted or dismantled from the motor
at one end and tool holder at the other end. The patented
sliding fit prevents axial stress on the inner shaft.
Our tool
holders suit different applications like mounting
of grinding wheels, mounted points sanding discs
and right angle attachments. The individual
components in the assembly of the tool holder are made with
proper heat treated, dimensional and surface finish, forms,
profiles etc.,
The separation
of drive unit and the tool itself provides for
complete freedom of operation, without fatigue,
during long working periods. Additionally, areas
difficult to reach with other tools can be worked effectively
with flexible shaft machines.
Our programme
embraces single and multi variable speed machines.
Operating speeds based on long, practical
experience provides for optimal cutting and
surface finish, which guarantees maximum stock removal
and also economic tool factor.
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Wednesday, 30 April 2014
Induction Motor
Monday, 17 March 2014
Induction Motor
Induction Motor
1.sunner india provides a Induction motors are simple and rugged in construction. Advantage of induction motors are that they are robust and can operate in any environmental condition.
Friday, 29 November 2013
The balanced threephase winding of the stator is supplied with a
balanced three phase voltage. As shown in the previous lesson (#29), the
current in the stator winding produces a rotating magnetic field, the
magnitude of which remains constant. The axis of the magnetic field
rotates at a synchronous speed ( n s = (2 ⋅ f ) / p ), a function of the
supply frequency (f), and number of poles (p) in the stator winding.
The magnetic flux lines in the air gap cut both stator and rotor (being
stationary, as the motor speed is zero) conductors at the same speed.
The emfs in both stator and rotor conductors are induced at the same
frequency, i.e. line or supply frequency, with No. of poles for both
stator and rotor windings (assuming wound one) being same. The stator
conductors are always stationary, with the frequency in the stator
winding being same as line frequency.
As the rotor winding is
shortcircuited at the sliprings, current flows in the rotor windings.
The electromagnetic torque in the motor is in the same direction as that
of the rotating magnetic field, due to the interaction between the
rotating flux produced in the air gap by the current in the stator winding, and the current in the rotor winding. This is as per Lenz’s
law, as the developed torque is in such direction that it will oppose
the cause, which results in the current flowing in the rotor winding.
This is irrespective of the rotor type used − cage or wound one, with
the cage rotor, with the bars shortcircuited by two endrings, is
considered equivalent to a wound one The current in the rotor bars
interacts with the airgap flux to develop the torque, irrespective of
the no. of poles for which the winding in the stator is designed. Thus,
the cage rotor may be termed as universal one. The induced emf and the
current in the rotor are due to the relative velocity between the rotor
conductors and the rotating flux in the airgap, which is maximum, when
the rotor is stationary ( nr = 0.0 ).As the rotor starts rotating in the same direction, as that of the
rotating magnetic field due to production of the torque as stated
earlier, the relative velocity decreases, along with lower values of
induced emf and current in the rotor. If the rotor speed is equal that
of the rotating magnetic field, which is termed as synchronous speed,
and also in the same direction, the relative velocity is zero, which
causes both the induced emf and current in the rotor to be reduced to
zero. Under this condition, torque will not be produced. So, for
production of positive (motoring) torque, the rotor speed must always be
lower than the synchronous speed.
The rotor speed is never equal to the
synchronous speed in an IM. The rotor speed is determined by the
mechanical load on the shaft and the total rotor losses, mainly
comprising of copper loss. The difference between the synchronous speed
and rotor speed, expressed as a ratio of the synchronous speed, is
termed as ‘slip’ An alternative explanation for the production of torque
in a threephase induction motor is given here, using two rules (right
hand and left hand) of Fleming. The stator and rotor, along with airgap,
is shown in Both stator and rotor is shown there as
surfaces, but without the slots as given in Also shown is the
path of the flux in the air gap. This is for a section, which is under
North pole, as the flux lines move from stator to rotor. The rotor
conductor shown in the figure is at rest, i.e., zero speed (stand
still). The rotating magnetic field moves past the conductor at
synchronous speed in the clockwise direction.
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Monday, 25 November 2013
In
the previous, i.e. first, lesson of this module, the formation of
rotating magnetic field in the air gap of an induction motor (IM), has
been described, when the three-phase balanced winding of the stator is
supplied with three-phase balanced voltage. The construction of the
stator and two types of rotor − squirrel cage and wound (slip-ring) one,
used for three-phase Induction motor will be presented. Also described
is the principle of operation, i.e. how the torque is produced.
Keywords:
Three-phase induction motor, cage and wound (slip-ring) rotor, synchronous and rotor speed, slip, induced voltages in stator winding and rotor bar/winding. After going through this lesson, the students will be able to answer the following.
Three-phase induction motor, cage and wound (slip-ring) rotor, synchronous and rotor speed, slip, induced voltages in stator winding and rotor bar/winding. After going through this lesson, the students will be able to answer the following.
This
is a rotating machine, unlike the transformer, described in the
previous module, which is a static machine. Both the machines operate on
ac supply. This machine mainly works as a motor, but it can also be run
as a generator, which is not much used. Like all rotating machines, it
consists of two parts − stator and rotor. In the stator (Fig. 30.1), the
winding used is a balanced three-phase one, which means that the number
of turns in each phase, connected in star/delta, is equal. The windings
of the three phases are placed 120° (electrical) apart, the mechanical
angle between the adjacent phases being [ ( 2 × 120°) / p ], where p is
no. of poles. For a 4-pole (p = 4) stator, the mechanical angle between
the winding of the adjacent phases, is [( 2 × 120°) / 4] = 120 ° / 2 =
60° , as shown in Fig. 29.4. The conductors, mostly multi-turn, are
placed in the slots, which may be closed, or semi-closed, to keep the
leakage inductance low. The start and return parts of the winding are
placed nearly 180° , or (180 ° − β ) apart. The angle of short chording (
β ) is nearly equal to 30° , or close to that value. The short chording
results in reducing the amount of copper used for the winding, as the
length of the conductor needed for overhang part is reduced. There are
also other advantages. The section of the stampings used for both stator
and rotor, is shown in Fig. 30.2. The core is needed below the teeth to
reduce the reluctance of the magnetic path, which carries the flux in
the motor (machine). The stator is kept normally inside a support.There
are two types of rotor used in IM, viz. squirrel cage and wound
(slip-ring) one. The cage rotor (Fig. 30.3a) is mainly used, as it is
cheap, rugged and needs little or no maintainance. It consists of copper
bars placed in the slots of the rotor, short circuited at the two ends
by end rings, brazed with the bars. This type of rotor is equivalent to a
wound (slip-ring) one, with the advantage that this may be used for the
stator with different no. of poles. The currents in the bars of a cage
rotor, inserted inside the stator, follow the pattern of currents in the
stator winding, when the motor (IM) develops torque, such that no. of
poles in the rotor is same as that in the stator. If the stator winding
of IM is changed, with no. of poles for the new one being different from
the earlier one, the cage rotor used need not be changed, thus, can be
same, as the current pattern in the rotor bars changes. But the no. of
poles in the rotor due to the above currents in the bars is same as no.
of poles in the new stator winding. The only problem here is that the
equivalent resistance of the rotor is constant. So, at the design stage,
the value is so chosen, so as to obtain a certain value of the starting
torque, and also the slip at full load torque is kept within limits as
needed.
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