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tends to condensate. At the same time pressure inside the enclosure will drop and cause humid air from the outside to penetrate non-hermetic polymer
gasket materials and cable glands. When the enclosure heats up again, only the vaporised water will escape, leaving more and more condensed water
inside the enclosure. This can lead to water build-up inside the enclosure and eventually cause malfunction. The phenomenon is illustrated in the figure,
with a cyclic temperature fluctuation.
Illustration 1.10: The pumping effect in tight enclosures
Build-up of water inside enclosures can be prevented by membranes that prevents fluids to penetrate but allows for vapour to pass, as known from fabrics
used for outdoor clothing. A special cable gland with this kind of material is offered by Danfoss to eliminate this problem. The cable gland should be used
in applications exposed to frequent temperature fluctuations and humid environments as in equipment used only during daytime where the inside tem-
perature tends to fall to the ambient temperature during the night.
1.2.8 Installation Flexibility
Danfoss decentralised solutions offers exceptional installation flexibility. Flexibility is supported by a number of benefits:
•
Mountable on Danfoss geared motors
•
Decentralised panel mounting possible
•
Handheld control panels
•
PC software for configuring and logging
•
Single or double sided installation
•
Service switch optional
•
Brake chopper and resistor optional
•
External 24 V backup supply optional
•
M12 connections for external sensors optional
•
Han 10E motor connector optional
•
Fieldbus support (Profibus DP V1, DeviceNet, As-Interface)
•
Compatibility with standard mains systems (TN, TT, IT, delta grounded)
For further details see the chapter on
The Decentralised Product Range
.
1 The Decentral Concept
VLT
®
Decentral FCD 300 Design Guide
12
MG.90.S1.02 - VLT
®
is a registered Danfoss trademark
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