3.3.6 Motor Compressors Cables
Correct dimensioning of motor compressor cable cross-
section and length is described in the application manual.
•
Use a screened/armoured motor compressor
cable to comply with EMC emission specifications
•
Keep the motor compressor cable as short as
possible to reduce the noise level and leakage
currents
•
Connect the motor compressor cable screen to
both the decoupling plate of the frequency
converters and to the metal cabinet of the motor
compressor
•
Make the screen connections with the largest
possible surface area (cable clamp). This is done
by using the supplied installation devices in the
frequency converter.
3.3.7 Electrical Installation of Motor
Compressor Cables
Screening of cables
Avoid installation with twisted screen ends (pigtails). They
reduce the screening effect at higher frequencies.
Cable length and cross-section
The frequency converter has been tested with a given
length of cable and a given cross-section of that cable. If
the cross-section is increased, the cable capacitance - and
thus the leakage current - may increase, and the cable
length must be reduced correspondingly.
Aluminium conductors
Aluminium conductors are not recommended. Terminals
can accept aluminium conductors but the conductor
surface has to be clean and the oxidation must be
removed and sealed by neutral acid free Vaseline grease
before the conductor is connected. Furthermore, the
terminal screw must be retightened after two days due to
the softness of the aluminium. It is crucial to keep the
connection a gas tight joint, otherwise the aluminium
surface will oxidize again.
3.3.8 Compressor Motor Protection
The electrical compressor motor protection is fully
provided by the frequency converter.
•
The frequency converter makes through an
Electronic current measurement anti-overload and
lock-rotor compressor motor protection (see
description in the application manual).
•
The frequency converter is protected against
short-circuits on compressor terminals T1, T2, T3.
•
If a mains phase is missing, the frequency
converter trips or issues a warning (depending on
the load).
•
If a compressor motor phase is missing, the
frequency converter trips.
•
The frequency converter is protected against
earth faults on compressor motor terminals T1,
T2, T3.
3.3.9 Access to Control Terminals
130B
T248.10
Illustration 3.16 B3, B4 and C3 Enclosures
130B
T334.10
Illustration 3.17 C1, B1 and B2 Enclosures
1.
10 pole plug digital I/O
2.
3 pole plug RS485 Bus
How to Install
Operating Instructions VLT
®
CDS302 and CDS303
MG34M302 - VLT
®
is a registered Danfoss trademark/Commercial Compressor
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