Product category:
Batteries, chargers and circuit protection
News Release from: REO (UK) | Subject: CNW output chokes
Edited by the Engineeringtalk Editorial
Team on 31 January 2002
Eliminate voltage problems with
frequency drives
A new range of output chokes will reduce or eliminate the voltage problems commonly found when using frequency drives to control AC induction motors
REO (UK) has introduced a new range of output chokes that will reduce or eliminate the voltage problems commonly found when using frequency drives to control AC induction motors Without an output choke, switching of the power transistors causes a rapid voltage increase which, ultimately, with lengthy cable runs, can have a negative influence on the dynamic regulation system of the inverter until it shuts down for protection reasons
This article was originally published on Engineeringtalk on 1 Mar 2001 at 8.00am (UK)
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Transient, high voltages with a rise rate of 3 - 6 kV/ms also originate from longer cable runs and consequently the motor insulation can be overloaded many times over.
Old and low cost motors cannot withstand this continuous overloading.
The new range of REO output chokes will effectively handle these common problems as well as having models specially designed to offer further specific solutions.
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For instance, the CNW 811 output choke dampens the asymmetric interference currents generated by inverters, without weakening the useful symmetrical current.
The EMC interference between 1 and 30 MHz is also significantly reduced.
For short cable runs, the CNW 811 provides an economical solution, suitable for installation in control panels which use electronic components, because the choke produces a very small stray field.
The CNW 823 is constructed to suppress rapid voltage rises, keeping them to the acceptable levels recommended for asynchronous motors in VDE 0530.
Consequently, the output choke prevents high voltage transients over longer cable runs.
The compact construction of the CNW 823 simplifies installation and means that it has fewer losses in comparison with conventional output chokes.
As a conventional output choke with good storage capacity the CNW 854 is recommended.
It works like a typical line inductor and smoothes the symmetrical effective current as well as the asymmetrical interference current.
The voltage increase is limited to less than 500V/ms and the voltage spikes between conductors at the motor terminal rail are less than 1000V.
This solution provides excellent suppression of mains conducted interference in the lower frequency range.
Electromagnetic emissions from the cable are heavily damped and both the losses and typical noise from the motor drive, caused by ripple, are reduced.
Finally, the CNW 856 is ideal for longer cable runs.
Building the CNW 856 into an IP22 enclosure has the advantage of providing safety protection and also helps to reduce the possibility of a fire hazard from hot components.
The separate input and output ports, together with neat, boxed appearance improve the aesthetics of the control panel layout. Request a free brochure from REO (UK) ...
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