Air-cooled Footprint ™-Generators for
Industrial Applications
Generator Services
Energy Service, Oil and Gas and Industrial Applications Services
Background
This Footprint-Concept is
applicable for:
Four-pole industrial
generators up to 25MVA
Independent from generator
manufacturer and type
With slip-ring or brushless
excitation
The four-pole industrial generators, built in the
past (before 1990) used for a power range up
to approx. 25MVA, more and more require
extensive reconstruction measures due to the
ageing of the components, e.g. rotor and stator
windings. In many cases, a safe operation of
these generators can no longer be ensured due
to aged insulation.
With frequencies 50Hz and
60Hz
Some of the possible repair measures e.g.
rewinding require a longer outage period.
With voltages 4KV to 16KV
The following figure shows the costs of some
repair measures for four-pole generators with
laminated drum rotors in comparison to the
Footprint-Generator costs.
With mechanical design that
is adapted to the respective
installation (shaft height,
anchoring, flange
connection, ventilation etc.)
Furthermore investigations have shown that
economically and technically, an exchange of
individual components as well as a reproduction
of the original machine is only suitable to a
limited extent.
For this reason a Footprint or exchange concept
was developed.
The Footprint-Concept combines state-of-theart generator technology with existing
interfaces of old generator types, considering
the operator’s commercial interests.
The basic idea is the integration of new
generators including new excitation systems in
existing plants.
The new machines meet all the relevant
interfaces of the current installation, (shaft
height, foundations etc.), thus allowing for a
quick exchange.
Modernization of Excitation systems
Increase of costs and extended delivery time for
spare parts and services related to legacy
excitation systems of generators give reason for
their modernization from an economic
perspective.
The various excitation systems with slip rings
and brushes, as well as DC-exciter sets,
employed in most cases are replaced by
modern, brushless three-phase AC- exciters.
Figure 1: Repair costs in comparison to the costs
for the Footprint-Generators
In addition, the exchange of analogue original
excitation systems with digital wear -free stateof-the-art systems can reduce operational costs
and at the same time can increase the
availability of the complete plant.
Answers for energy.
Typical Applications for the FootprintConcept
Some typical industrial generators, which
fit into this concept, are shown in the
following figures.
Figure 2: Generator 4,500KVA, 6,300V,
cos = 0.8, slip-ring excitation 45V, 520A,
1,500rpm
Potential Benefits for the Operator
Altogether, the Footprint-Concept offers
the following benefits:
• Short outage period (resulting from
adapted design to the respective
installation like shaft height, anchoring,
flange connection, ventilation etc.)
• Reduced operational costs (for
maintenance e.g. by decreasing the
maintenance intervals, insurance, etc.)
• Flexible adjustment of design and
cooling system
• Increased operational safety and plant
availability (due to new components)
• Extension of plant life time
• Increased performance (active and
reactive power – possible on demand)
• Increased efficiency respectively
decreased power losses
Additional potential benefits after
exchanging the legacy excitation system:
• Reduced operational costs (also for the
excitation system)
• Reduced contamination (due to carbon
dust)
• Reduced wear parts (stock-keeping)
• Abolition of exciter bearing
References
The Siemens experiences are based on
more than 1,000 air-cooled generators
with laminated drum rotors which are in
operation worldwide.
The Footprint-Concept has already been
implemented in about 30 plants.
For more detailed information
please contact your local Siemens
sales representative or send us an
email to:
support.energy@siemens.com
Figure 3: Generator 18,040KVA, 6,930V,
cos = 0.8, brushless excitation 80/200V,
8/16A, 1,800rpm
Figure 4: Generator 18,000KVA, 6,300V,
cos = 0.8, brushless excitation
113/159V, 3.7/5.2A, 1,500rpm
Figure 5: Side view of Footprint-Generator with brushless excitation (exciter in overhang
without an additional bearing)
Published by and copyright @ 2014
Siemens AG, Energy Sector
Econova-Allee 3
45356 Essen, Germany
Siemens Energy, Inc.
4400 Alafaya Trail
Orlando, FL 32826-2399, USA
For more information, contact our
Customer Support Center.
Phone: +49 180/524 70 00
Fax:
+49 180/524 24 71
(Charges depending on provider)
e-mail: support.energy@siemens.com
Document name: Footprint-Generators for Industrial
Applications
Order no. E50001-G510-A245-X-7600
All rights reserved.
Trademarks mentioned in this document are
the property of Siemens AG, its affiliates, or
their respective owners.
Subject to change without prior notice.
The information in this document contains
general descriptions of the technical options
available, which may not apply in all cases.
The required technical options should
therefore be specified in the contract.