Xylem IM255 AQUAVAR Intelligent Pump Controller - Manual (Page 34)

wire between terminals 18 (DI 18, parameter 5-10) and 12 (24V dc). A start command is
given to the controller when terminal 18 is connected to 24V.
Using screened control cables
Correct screening
The preferred method in most cases is to secure control and serial communication cables
with screening clamps provided at both ends to ensure best possible high frequency
cable contact.
If the earth potential between the frequency converter and the PLC is different, electric
noise may occur that will disturb the entire system. Solve this problem by fitting an
equalizing cable next to the control cable. Minimum cable cross section: 6 AWG or 16
mm
2 .
Figure 14: Correct screening
1 Min. 6 AWG or 16 mm 2
2 Equalizing cable
50/60 Hz ground loops
With very long control cables, ground loops may occur. To eliminate ground loops,
connect one end of the screen-to-ground with a 100 nF capacitor (keeping leads short).
Figure 15: 50/60 Hz ground loops
Avoid EMC noise on serial communication
This terminal is connected to earth via an internal RC link. Use twisted-pair cables to
reduce interference between conductors.
Figure 16: Twisted-pair cables
1 Min. 6 AWG or 16 mm 2
2 Equalizing cable
Alternatively, the connection to terminal 61 can be omitted:
Figure 17: Twisted-pair cables without terminal 61
Electrical Installation
32 Aquavar ® Intelligent Pump Controller INSTRUCTION MANUAL