Product category:
Stepper and Servo Drives, Motors, Controls
News Release from: Voith Turbo | Subject: H-DAKS
Edited by the Engineeringtalk Editorial
Team on 22 April 2005
Shrink for steam turbine servomotors
High-pressure steam turbine servomotors can now be built even more compactly following the development of new servomotors where the stroke has been shortened from 120 to 60mm.
High-pressure steam turbine servomotors (H-DAKS) can now be built even more compactly following the development of new servomotors where the stroke has been shortened from 120 to 60mm As a result, the plate valve previously necessary for high oil flow volumes can be eliminated, saving components and increasing reliability
This article was originally published on Engineeringtalk on 2 Sep 2003 at 8.00am (UK)
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Instead of the spiral spring needed for stroke reduction, cup springs with increased spring ratings and lower tolerances can be used.
Additionally, Voith Turbo has also improved the control behaviour and the fast closing function.
High-pressure servomotors are also suitable for applications at larger steam turbines.
At steam turbines, electrohydraulic Voith servomotors precisely and highly dynamically control the steam supply and, when necessary, also the bleeding of steam.
At a load increase during the turbine operation (trip), the control valve of a medium-size steam turbine need to shut safely within 300ms.
Larger steam turbines require even shorter closing times because of their higher mass flows.
The control valve of the newly developed high-pressure servomotors can be shut well within the required time of 300ms.
This fast reaction occurs without undershoot, which reduces the load on the valve seat.
Additionally, applications with gas turbines, where extremely precise fuel dosage is required, are now also possible.
For the first time, an improved pilot control has been implemented into the new Voith servomotors.
This pilot control which has been tested in numerous trials has a higher magnet force, while the current uptake stays the same.
Consequently, a harder control spring with higher energy storage can be used.
The result: especially in the small signal range, the control behaviour is more dynamic and more stable against friction influences and reactions of the hydraulic fluid.
The adherence to even closer production tolerances for the components of the hydraulic pilot valve has led to a considerable reduction of oil leakages from 4 to 2.5 litre/min.
This pays off for the operator, because it means that the hydraulic pumps can be designed with lower dimensions.
Another innovation is the option to use flame-resistant hydraulic fluids which results in more favourable premium payments for fire insurance contracts.
As an option, the new high-pressure servomotors are also available in explosion-proof design.
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