|
BENEFITS: Size
Though
physically smaller than conventional systems of resistors and contactors,
the large thermal capacity of Magnastart permits the starting of
difficult and high inertia loads without problems.
Simplicity
Magnastart requires only one shorting
contactor, reducing the system complexity, size and cost.
Performance
Magnastart is ideal for inching, reversing,
and plug braking without any additional rotor controls.
Maintenance
Magnastart Inducers have no moving parts, and
do not use liquids or chemicals, or need anti-freeze for exposed use.
Magnastart will give many years of service without any maintenance
or adjustment.
Reliability
The robust construction permits heavy usage under
the most arduous conditions. Built-in thermal cut-out provides protection
against damage.
Flexibility
Each Inducer model is designed to start a wide range
of motors. The front panel allows the user to select the exact starting
torque and stator current required, on commissioning if appropriate.
Unlike resistors, the total energy capacity of Magnastart remains
constant regardless of the impedance tapping selected.
Smooth
acceleration
Smooth acceleration to
full speed reduces electrical and mechanical stresses in the motor and
drive.
HOW
MAGNASTART WORKS:
The Magnastart
Inducer consists of 3 coils wound on specially shaped steel cores. Eddy
currents in these cores are reflected in the windings as an impedance
which is dependent on rotor frequency. This is connected across the rotor
windings on starting (figure below).
When power is applied to the
stationary motor, the frequency in the rotor is the same as the stator
resulting in the maximum Inducer impedance. As the machine accelerates,
the rotor frequency (the slip frequency) and Inducer impedance decrease.
This results in a smooth acceleration (bottom figure) to nearly full speed
at which point the rotor is short circuited by the rotor contactor.
The starting power is dissipated in
the heavy mass of the steel cores, which allows the inducer to absorb a
considerable amount of energy. Advanced thermal insulation protects the
coils which remain relatively cool, and several consecutive starts may be
obtained on drives with high inertial loads.
Each of the coils has four
connections brought out to studs on the front panel. By using various star
and delta combinations up to 17 different starting impedances are
available, to provide the exact starting characteristics required on a
wide range of motors.
Magnastart PDF
Brochure
 View
Now
SPECIFICATIONS:
APPLICATIONS:
Magnastart Inducers are intended to be
built in to slipring motor starter equipment by the customer to satisfy
the technical requirements of the specific motor and load. They may also
be retro-fitted into existing rotor starter systems to replace failed
starter equipment. (The product design was previously known as
Citostart).
In normal application the Magnastart is
connected across the rotor windings, selecting the impedance to suit the
starting current/torque requirements. A shorting contactor operated by a
timer is connected across the Magnastart, to short out the rotor once near
full speed is reached.
During commissioning, test starts
followed by adjustment of Magnastart tappings allow the best balance
between start current and run-up time to be achieved. Like all
purpose-built electrical control systems, the system design requires the
consideration of an experienced electrical engineer.
Magnastart design aspects that should be
addressed include: ·
-
Stator current overload
protection and co-ordination with starting surge
-
Matching rating of Magnastart
Inducer to rotor and duty cycle
-
Setting Magnastart impedance to
meet run-up time, current and torque requirements · Timing of rotor
shorting contactor for full-speed operation
-
Controls and protection in case
of rotor stall or overload during starting
Magnastart
Installation PDF
Documentation
The Brochure and Application
Guide require you to have the ability to read PDF files. A viewer (Acrobat
Reader) which will also allow you to save and print the files locally may
be downloaded for free from Adobe at http://www.adobe.com/products/acrobat/readstep.html.
Magnastart is a Tradename of ADWEL International Ltd ©
ADWEL International Ltd 2007
| 
