MCSD units are easily incorporated into automatic
calibration systems and offer precision operation and high production
rate performance. The MCSD range also fully demagnetises many types of
permanent magnet with an exponentially decaying sinusoidal waveform.
The MCSD series also has the ability to set or age
magnets. This takes the form of a uni-directional pulse of the opposite
polarity to the magnetisation pulse. This pulse knocks the magnet back
along its hysteresis curve. This can either be a fixed energy set
pulse, for artificial aging, or a calibrated set pulse where a
Fluxmeter or Gaussmeter provides feedback to the system.
Their easy to use versatility makes them ideal for
laboratories needing to develop and support permanent magnet based
products. The MCSD range has 2x RS232 ports suitable for SPC data
collection as standard and PLC control.
The MCSD unit is fully microprocessor controlled with
adjustable capacitor voltage from 50 to 3,000v (in 1v steps) with
feedback via a digital voltage display. It utilises non-polarised
capacitors that are discharged into a fixture or coil. The
microprocessor controls the charging and discharging of the machine
ensuring that the charging is managed in a way to reduce the initial
charge current that non-microprocessor systems may not have. The
microprocessor also performs fault monitoring for system protection.
Each MCSD unit is fitted with an internal dump resistor
to discharge the main capacitors in power down or abort mode, ensuring
a safe environment for both operator and machine.
Principles of operation
In most applications the required current is too large
to be directly driven from the mains and/or the fixture’s
inductance/resistance is such that not enough current would flow to
produce the required magnetic field. A capacitor bank is, therefore,
charged to the required voltage level (up to 3,000 volts) and this
stored energy is then discharged by a thyristor into the fixture to
produce the required magnetic field.
In a magnetising operation a clamp or freewheel diode is
placed across the fixture to ensure no reverse energy charges the
capacitor bank negative. All the energy is dissipated into the fixture
is a magnetisation pulse.
In a demagnetisation operation the free wheel diode is
placed in parallel with the thyristor to cause a ringing or decaying
In set mode the freewheel diode is removed to provide a
Reverse polarity circuits ensure that the energy can be
discharged either way through the fixture to provide pulses of either
Ignitron outputs will be offered instead of
semiconductor devices if the peak current is exceedingly high and/or
the rise time of the pulse is very short.
Ignitrons may also be offered for machines where the
fixture is “unknown” or where fault conditions are expected that could
damage semiconductor output devices.
The MCSD series is controlled by means of a keypad
during normal operation or via an RS232 / PLC port when under remote
control. Using four different modes of operation the MCSD series can
quickly charge, demagnetise or when used with suitable external
hardware (Gaussmeter / Fluxmeter) calibrate magnets.
Modes of Operation
Charge Mode is used to charge
(saturate) magnets using a uni-directional pulse of energies up to the
maximum allowable. The operator selects the operating voltage and the
MCSD series discharges into the magnetising fixture whenever the pulse
button is pressed. The capacitor voltage is displayed on the front
panel during this process and can be altered at any time to a new value.
Demag Mode is used to demagnetise
work pieces using a decaying sinusoidal waveform.
Set mode is used to set the flux
level of a work piece to a particular value. This mode offers control
of the demagnetising pulses. Demagnetising pulses are generated
starting with the minimum voltage, the operating voltage being
increased automatically by the selected step size after each pulse up
to the selected maximum.
Cal mode is similar to set mode with
the addition of an initial charge pulse of the maximum allowable
energy. This pulse is used to saturate the work piece to a flux level
greater than the final required flux level. The sequence of
demagnetising pulses that follow the charging pulse can then be used to
set the magnets to a correct flux level in one continuous overall
Using decaying sinusoidal wave forms to demagnetiser or
calibrate magnets will produce a more stable magnet than achieved
through demagnetising with uni-directional pulses with a reversed
The MCSD series has several memories in each mode that
can be used to store different operating voltages. These can be used to
set up the machine quickly and easily for processing different
At any time during operating the MCSD series can be
forced to abort any operation currently in progress and enter a safe
state. The capacitor energy is safely dumped into an internal dummy
load and the machine becomes inactive until the operator continues
using the machine.
To reduce unnecessary power consumption, the MCSD series
has a built in automatic “timeout” function. After three minutes of
non-use the capacitor voltage is dumped and the MCSD enters a safe
The magnetiser energy will be selected to meet the
requirements of the application and will be dependent on the fixture
The typical range of energy outputs for MCSD units span
from 100J to 20kJ.
The MCSD series can be interfaced to standard Hirst Gaussmeters and
Integrating Fluxmeters for the purpose of auto calibration. Using this
type of system, after the initial preset values for output pulses are
entered, the entire calibration of the magnet involves just one press
of the PULSE button.
The MCSD can store information about each magnet, continuously
uploading this data to a remote computer for analysis. If a Gaussmeter
or Fluxmeter is interfaced to the MCSD information such as final flux,
calibration voltage etc can be collected for statistical analysis.
The MCSD series can be provided with a PLC port to provide remote
operation of the unit using digital inputs and outputs. The PLC control
can be part of a mechanical handling system or integrated with a Hirst
Gaussmeter or Integrating Fluxmeter to provide a fully automated system.