Aggressive Environments; Calculation Of Resulting Reference - Danfoss VLT 7000 Series Manual

Aggressive environments

In common with all electronic equipment, a frequency
converter contains a large number of mechanical and
electronic components, all of which are vulnerable
to environmental effects to some extent.
The frequency converter should not
therefore be installed in environments
with airborne liquids, particles or gases
capable of affecting and damaging the electronic
components. Failure to take the necessary protective
measures increases the risk of stoppages, thus
reducing the life of the frequency converter.
Liquids can be carried through the air and condense in
the frequency converter. In addition to this, liquids may
cause corrosion of components and metal parts.
Steam, oil and salt water may cause corrosion
of components and metal parts.
In such environments, equipment with enclosure
rating IP 54 is recommended.
Airborne particles such as dust particles may
cause mechanical, electrical or thermal failure
in the frequency converter.
A typical indicator of excessive levels of
airborne particles is dust particles around the
frequency converter fan.
In very dusty environments, equipment with
enclosure rating IP 54 or a cabinet for IP 00/20
equipment is recommended.

Calculation of resulting reference

The calculation made below gives the resulting
reference when parameter 210 Reference type is
programmed for Sum [0] and Relative [1], respectively.
External reference can be calculated as follows:
(Par. 205Max. ref . - Par. 204 Min. ref.) x Ana. signal Term. 53 [V] +
Ext. ref. =
Par. 310 Term. 53 Max. scaling - Par. 309 Term. 53 Min. scaling
(Par. 205 Max. ref. - Par. 204 Min. ref.) x Par. 314 Term. 60 [mA]
Par. 316 Term. 60 Max. scaling - Par. 315 Term. 60 Min. scaling
Par. 210 Reference type is programmed = Sum [0].
Ext. ref. =
(Par. 205 Max. ref. - Par. 204 Min. ref.) x Par. 211-214 Preset ref.
Par. 210 Reference type is programmed = Relative [1].
External reference x Par. 211-214 Preset ref.
Res. ref. =
MG.70.A1.02 - VLT is a registered Danfoss trademark
VLT® 7000 Booster
In environments with high temperatures and humidity,
corrosive gases such as sulphur, nitrogen and
chlorine compounds will cause chemical processes
on the frequency converter components. Such
chemical reactions will rapidly affect and damage
the electronic components.
In such environments, it is recommended that
equipment is mounted in a cabinet with fresh
air ventilation, keeping aggressive gases away
from the frequency converter.
reduce the life of the converter.
Before the installation of the frequency converter, the
ambient air should be checked for liquids, particles
and gases. This may be done by observing existing
installations in this environment. Typical indicators of
harmful airborne liquids are water or oil on metal
parts, or corrosion of metal parts.
Excessive dust particle levels are often found on
installation cabinets and existing electrical installations.
One indicator of aggressive airborne gases is blackening
of copper rails and cable ends on existing installations.
External reference is the sum of references from
terminals 53, 54, 60 and serial communication.
The sum of these can never exceed parameter
205 Max. reference.
+
+
+
100
+
100
NB!:
Mounting frequency converters in aggressive
environments will increase the risk of
stop-pages and furthermore considerably
(Par. 205 Max. ref. - Par. 204 Min. ref.) x Ana. signal Term. 54 [V]
Par. 313 Term. 54 Max. scaling - Par. 312 Term. 54 Min. scaling
serial com. reference x (Par. 205 Max. ref. - Par. 204 Min. ref.)
16384 (4000 Hex)
External ref. + Par. 204 Min. ref . + Par. 418/419 Set-
point (only in closed loop)
Par. 204 Min. ref. + Par. 418/419 Setpoint (only in closed loop)
+
117