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A Well-Tried Principle At
the heart of an EM stabiliser, a transformer has its secondary winding conncted
between the mains supply and the load, with the primary winding voltage controlled
by a motor-driven variable transformer. A solid state servo-amplifier continuously
monitors the output voltage of stabiliser , and any error voltage is amplified
to operate the servo motor of the variable transformer, driving its brushgear
to a point where it is injecting a voltage that will correct the supply voltage
by adding or substracting from it.
For many years our on-going development
programme has enhanced the performance of the EM range, moving it further and
further ahead of competitors. An early breakthrough using thyratron valves in
1957 gave us 40 time faster response speeds and in 1963 we patented a solid state
control system to achieve a remarkable 129 times faster response. This original
power transistor concept has been continuously improved with the introduction
of the latest semiconductor technology, and now incorporates velocity feedback
for even faster correction. So today's EM range servo system brings you exceptionally
fast response with controlled deceleration to minimise overshoot. If you need
even faster action we can provide it via our unique solid state ranges, but for
the vast majority of applications EM response speeds are more than sufficient,
taking into account the time constant of power supplies, motors, etc, making up
the load.
Over six thousand models span 1KVA to 8.000KVA output ratings, single
or three phase, incorporating full spike and interference suppression, if required.
Key Features - Output
Voltage Accuracy: ±0.5%(0.1% if required). Accuracy maintained over the full
range of input voltage variations from zero to full load irrespective of power
factor, frequency variations, and ambient temperature variations from -15 to +45°C(Temperature
coefficient 0.003%/°C). Three phase stabilisers will, in additions to the above,
maintain the accuracy of each pahse, both line tot line and line to neutral, even
if the input voltage, load and power factor are totally unbalanced.
- Ultra
fast response
- Low internal Impedance capable of sustaining
high surge currents.
- Efficincy better than 98% with up to 99.5%
for larger models.
- Waveform Distortion negligible with any type
of load.
- Soft start ensures low voltage at the moment of switching
on. Without this facility, particularly with wide swing stabilisers, voltage surges
of 85% or more can occur.
- Soft stop dampens the force of impact
when the brush gear reaches the end stop. Essential on larger high speed stabilisers
to prevent brush bounce resulting in RFI or even Variable Transformer burn out.
- Full
transverse and common mode spike/interference suppresion when required.
-
Oil immersed version for outdoor or for use in hostile environments.
- Wide
range of optional extras including the latest no break by-pass technology.Distribution
boards and any other feature to costumers requirements can be built into the cabinet.
- EMT
series stabilisers incorporate the advance ROTAVOLT technology and aditional cooling,
resulting in a considerable coast and weight reduction per KVA. All models are
supplied with the soft start option fitted as a standard. In the event of impeded
ventilation the unit will continue to eperate at a reduced output voltage whilst
sounding an alarm.
Three phase models:
EM three phase stabilisers are normally supplied for "star" connection
and require an incoming neutral. if no neutral is available a static balancer
will be fitted to the stabiliser. if the load also requires a neutral a larger
balancer can be provided. Full accuracy of each phase will be maintained both
line to line and line to neutral under all conditions of unbalance. This is often
not the case with other makes of stabilisers. Speed
of response
Defined as the time taken to restore a 10% voltage variation
to within 2%. EM stabilisers are the most cost effective and efficent method of
obtaining an undistorted stable mains supply. The speed of response is sufficient
for most applications taking into account the time constant of power supplies,
motors and other components making up the load. Specifying the speed of correction
in terms of "volts per second" or "% per second" is misleading as it details the
maximum rate of correction that the servo drive can reach, ignoring the time taken
for the drive to reach full speed and slow down again. For faster speeds of response
specify our "BE" range of solid state stabilisers. |
