Trade fairs - Lenze

18
Technology
Curbing electricity costs
Motors are classified according to power consumption/
Speed control reduces life-cycle costs still further
Industrial electricity prices have rocketed
in Europe recently, with rises of up to
35 per cent. This makes it worth considering
ways of saving electricity which
really pay off.
According to the German Electrical and
Electronic Manufacturers’ Association
(ZVEI), electrical drive systems consume
around two-thirds of all industrial electricity.
Power consumption can be
reduced considerably using efficient
motors and inverters for controlling
speeds. In fact, speed regulation
accounts for around a third of the overall
potential savings. Energy-saving
motors constitute another ten per cent,
while the reduction of mechanical losses
represents the lion’s share at 60 per cent.
Nowadays around a third of all drive
systems sold are speed-controlled,
although barely ten per cent of those
already at work in the factories themselves
are speed-controlled, a figure
which is increasing as older systems are
replaced and modernised. One of the
factors which has brought about this
change is the consideration of processes,
expenses and therefore costs throughout
the entire life cycle of machinery.
Lenze has dealt systematically with
the theme of life cycle costs over recent
years. After analysing a typical life cycle,
cost factors which can be influenced by
drive systems are identified and systematically
reduced in the development of
products and processes. This in turn produces
financial benefits for machine
builders and operators.
Lenze will be classifying its motors
according to energy consumption from
now on. CEMEP, the European Committee
of Manufacturers of Electronic Machines
and Power Electronics, has established a
system of categorising electrical motors.
Motors are allocated to Efficiency Classes
1, 2 and 3. Class 1 is only for motors with
extremely low losses and therefore low
operating costs. All of Lenze’s MCS synchronous
servo motors already fall well
within this category. This means a reduction
of energy losses of up to 40 per
cent in comparison with conventional
Class 3 motors.
However, surveys have shown that
steps to improve the power efficiency of
motor systems are often neglected,
even where they would be extremely
profitable. One of the reasons for this is
that life-cycle costs are given too little
consideration when investments are
made. Long-term potential savings
brought about by reduced power consumption
are often ignored. The German
Electrical and Electronic Manufacturers’
Association aims to promote a
sustainable way of looking at this mat-
ter and has to this end recruited experts
whose job it is to work out how energy
can be used more efficiently. The framework
for this is provided by the European
regulations entitled “Definition of
requirements for the environmentally
compatible design of electrically powered
products”.
The Executive Committee of the
ZVEI has laid down a general strategy
based on three pillars. “We are continuing
to focus on efficiency-optimised,
low-loss motors and in particular on
speed regulation in order to achieve an
optimum operating point adjustment
under partial loads as well as full load,”
explains Dr. Edwin Kiel, Director of
Innovation at Lenze AG and also Head of
the “Energy efficiency in drive technology”
work group at ZVEI. “The third
pillar is continuing to increase people’s
awareness of this issue, and pursuing
collaborative ventures with users and
other related engineering disciplines,”
says Dr. Kiel in summary.
Three steps to saving
energy
˘ Only use motors of Efficiency Class 1
or 2.
˘ Friction-type connections between
gears and motors (geared motors)
reduce mechanical losses.
˘ Combine the motor with a frequency
or servo inverter so that it can be
operated in accordance with
demand.
Perfectly engineered electrical motors
reduce power consumption.