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Eddy Current Variable Speed Drive [0.2 kW to 11 kW Integral Design]
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"POWERMAG" consists of a totally enclosed, fan cooled (TEFC),
flange type three-phase squirrel cage induction motor is mounted on to an
eddy current cluth, having a projected, self-ventilated common frame design.
There is no physical contact between motor and clutch. This results in smooth
response, there by eliminating shock loading and extending equipment life.
"POWERMAG" eddy current variable speed drive operates on AC power supply and provides constant torque at variable speeds over a wide range.
"POWERMAG" eddy current variable speed drives are economial and widely used for various industrial applications.
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15 kW to 110 kW Integral Design
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The
primary elements of POWERMAG eddy current variable speed drive are an AC motor,
an eddy current clutch, a tacho generator and a seperate small solid-state
state electronic controller. The eddy current clutch consists of two rotating
members : drum driven at constant speed by the AC motor and within the drum,
a rotor / output shaft which connected to the load. Torque is transmitted
from the drum to the rotor / shaft through an adjustable magnetic field that
attracts the two members. The magnetic field is produced by a clutch coil
typically below 2% of the total drive power requirements which means smaller
and longer-life controller circuits can be used.
All POWERMAG eddy current variable speed drives have an integral tacho generator mounted around the output shaft, to give voltage and frequency proportional to speed, which is used for speed reference feed back signal to the controller and maintains the output speed within 2% for the load changes form 10% to 100%. It can also be used for speed indication.
SPEED
HOLDING ACCURACY - Closed loop speed control is very accurate. It is achieved
by comparing a reference signal with the feedback signal from the tachogenerator
mounted on the POWERMAG drive. Any difference or error between these signals
causes the output stage SCR to adjust the coil current, there by maintaining
the set speed within 2% for load changes from 100% to 10%.
| Modular Design |
In
this design, POWERMAG is offered as an independent eddy current coupling with
input and output shafts. The input can be driven from a standard foot mounted
induction motor suitably arranged on a common bed-plate.
This is a versatile design in which the motor can be mounted-in-line, alongside
or on top of "POWERMAG" coupling.
| Modifications |
Standard type POWERMAG
footmounted self-ventilated aircooled eddy current variable speed drives may
be furnished with
| Priview of Structure |
| Typical Torque-Speed Curve |
| Power Saving Drive |
Centrifugal
loads like pumps, fans and blowers torque is propotional to square of the
speed and the required power is proportional to the cube of the speed. So
unlike in constant torque applications the Eddy current drive's fixed speed
motor which provides power to the eddy current clutch portion does not have
to develop the rated torque when the speed is lowered. In other words the
power drawn from the line follows generally a cube law since the centrifugal
load demands power in proportion to third power of speed. This fact is the
same for AC variable frequency drive, DC drive and eddy current drive.
A superiority of 6% only can be claimed by AC variable frequency drive and
DC drive over eddy current drive.
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FEATURES |
BENEFITS |
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Torque is transmitted by a magnetic field without friction or wear providing longer life. |
Less Down time |
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Tachogenerator feedback maintains the output speed within 2% for load changes from 10% to 100% |
Controls Speed accurately |
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Approximately 200% motor torque available at clutch output |
Accelerates high inertia loads quickly and handles intermittent overlaods without having to increase the horsepower rating. |
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Rugged AC motor is the main drive member. Permanently lubricated bearings |
No routine maintenance |
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Fewer wearing parts – all POWERMAG drives have only four bearings |
High reliability and low maintenance. Minimum down-time and maximum production from initial start-up reduce annual operating costs and accumulate savings over protracted years of service |
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Simple design – drive consists of a clutch. AC induction motor and small solid state controller |
Easy to understand, install, operate and maintain |
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Stationery field design – eliminates all weak links like commutators, slipring or brushes |
Enhancing life expectancy |
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All rotating members are dynamically balanced |
Extremely low vibration and long bearing life |
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Motors starts of Load |
Reduce mains peak demands |
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Constant cooling over whole speed |
Eliminated external cooling fans |
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Wide speed range at constant torque |
Accurate rpm control throughout the speed range of 10:1 for continuous operation and 20:1 for short operation at full load 100% rated torque. |
| Applications for Powermag E C Drive |
POWERMAG
EC drives are economical and widely used for various industrial applications
Cement, Rubber, Chemical, Plastic, Paper, Wire drawing, Mining,Thermal power
plants, Blowers, Extruders, Kilns, Material Handling, Pumps, Screw Feeders,
Conveyors, Sugar, Tea, Tobacco etc.,
POWERMAG is an simple drive,easily installed and maintained, longlife with
no routine maintenance.
| Cement Industry |
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Calendar drive |
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Paper Industry |
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Chemical fibre Industry |
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Mining Industry |
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Other Industries |
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Printing machine drive |
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Warper drive |
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Rubber and chemical industries |
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Electric Wire making |
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Operation of tubing machine, extruder, wire winding etc. |
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Torque control of wire drawing machine |
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Speed control of copper casting machine |