Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive (A Frame) - ForGe Control - Manual (Page 193)

Rockwell Automation Publication 7000A-UM200C-EN-P - June 2014 193
Appendix
G
Environmental Considerations
Air Quality Requirements Air cleanliness for PowerFlex 7000 drives is important for two reasons:
1. Airborne particulate that settles on heat sinks and heat-producing
components increases the thermal resistance of the components, resulting
in an increase in the temperature of the part. The internal fins of the
hockey puck thyristor heat sinks must be kept clean; the dust on the
surface of the heat sinks interferes with the boundary layer air flow which
inhibits cooling of the part.
2. Particulate can decrease the tracking insulation of electrical insulation
materials within the drive. Electrically conductive dusts (such as coal dust
and metallic dusts) can be severe, however other particulates such as
cement dust moist from high ambient relative humidity may prove
destructive as well. Dusts coating low voltage circuit boards can cause
failures too.
Air presented to the PowerFlex 7000 must be of a cleanliness expected in a typical
industrial control room environment. The drive is intended to operate in
conditions with no special precautions to minimize the presence of sand or dust,
but not in close proximity to sand or dust sources. This is defined by IEC 721
(1)
as being less than 0.2 mg/m3 of dust.
If outside air does not meet the conditions described above (0.2 mg / m3), the air
must be filtered to ASHRAE (American Association of Heating, Refrigeration
and Air-Conditioning Engineers) Standard 52.2 MERV 11 (Minimum
Efficiency Reporting Value). This filtration eliminates from 65…80% of the
particulate in Range 2 (1.0…3.0 μm) and 85% of the particulate in Range 3
(3.0…10.0 μm). This filter system must be cleaned or changed regularly.
This environment is accomplished by placing the drive in a pressurized room
with adequate air conditioning to maintain the ambient temperature. The drive
exhaust air is circulated within the control room. Five to ten percent cooled/
heated and filtered make-up air is usually provided to keep the room pressurized.
(1) IEC 721-3-3 “Classification of Environmental Conditions - Part 3: Classification of Groups of Environmental Parameters and their
Severities - Section 3: Stationary Use at Weather Protected Locations”.