Installation Of Misc. Connections - Danfoss VLT HVAC Drive FC 102 Design Manual

How to Install
Standard mitigation strategies
•
Use an insulated bearing
•
Apply rigorous installation procedures
Ensure the motor and load motor are aligned
Strictly follow the EMC Installation guideline
Reinforce the PE so the high frequency
impedance is lower in the PE than the input
power leads.
5 5
Provide a good high frequency connection
between the motor and the adjustable frequency
drive by shielded cable, which has a 360°
connection in the motor and adjustable
frequency drive
Ensure that the impedance from adjustable
frequency drive to building ground is lower than
the grounding impedance of the machine. Make
a direct ground connection between the motor
and load motor.
•
Apply conductive lubrication
•
Try to ensure that the line voltage is balanced to
ground. This can be difficult for IT, TT, TN-CS or
Grounded leg systems
•
Use an insulated bearing as recommended by the
motor manufacturer
NOTICE!
Motors from reputable manufacturers will typically have
these fitted as standard in motors of this size.
If none of these strategies works, consult the factory.
If necessary after consulting Danfoss:
•
Lower the IGBT switching frequency
•
Modify the inverter waveform, 60° AVM vs.
SFAVM
•
Install a shaft grounding system or use an
isolating coupling between motor and load
•
Use minimum speed settings, if possible.
•
Use a dU/dt or sinus filter
166
Design Guide

5.5 Installation of Misc. Connections

5.5.1 RS-485 Bus Connection
One or more adjustable frequency drives can be connected
to a control (or master) using the RS-485 standardized
interface. Terminal 68 is connected to the P signal (TX+, RX
+), while terminal 69 is connected to the N signal (TX-,
RX-).
If more than one adjustable frequency drive is connected
to a master, use parallel connections.
Figure 5.101 RS-485 Connecting Multiple Adjustable
Frequency Drives to Master
In order to avoid potential equalizing currents in the
shield, ground the cable shield via terminal 61, which is
connected to the frame via an RC link.
For EMC-compliant installation, refer to chapter 5.7 EMC-
compatible Installation.
Bus termination
The RS-485 bus must be terminated by a resistor network
at both ends. Set switch S801 on the control card for "ON".
For more information, see chapter 5.2.16 Switches S201,
S202, and S801.
Communication protocol must be set to 8-30 Protocol.
Danfoss A/S © Rev. 2014-01-13 All rights reserved.
RS 232
68 69 68 69
+
USB
-
RS 485
68 69
MG16C122