Power Supply And Bus Cable - HEIDENHAIN TNC 410 M Technical Manual

4.8 +5 V Power Supply and Bus Cable
April 2007
Warning
The following constraints apply to supply lines and bus cables:
Maximum length for unit bus cable (X79) is 1 m each, starting from X79
of the inverter.
Maximum length for supply bus cable (X69) is 5 m.
Maximum length for PWM cable (X111/X112) is 5 m.
Maximum length for +5 V litz wires (X74): Line drop < 100 mV. Ensure
that the cross section of the litz wires for the +5 V supply is large enough.
The current consumption (+5 V) of the consumers can be found in the
Specifications.
The terminals for the +5 V litz wires (X74) are suitable for a maximum
cross section of 4 mm
terminal pins must be used.
Example for calculating the cross section of the +5 V litz wires (X 74):
Components used
MC 422B (single-processor with position
inputs)
CC 422 (6 control loops)
6 x ERN (speed)
3 x LS (axes, position)
2 x ROD (axes, position)
R = U / I = 0.1 V / 8.75 A = 0.0114 ohms
where rho of copper = 0.0179 (ohm x mm
and the required wire length: l = 3 m
R = (rho x l) / A;
A = (rho x l) / R = (0.0179 (ohm x mm
This results in a required cross section of 4.7 mm
+5 V Power Supply and Bus Cable
2
. If the cross sections are larger, corresponding
2
) / m
2
) / m x 3m) / 0.0114 ohms = 4.7 mm
Current consumption
5.2 A
1.5 A
6 x 0.2 A = 1.2 A
3 x 0.15 A = 0.45 A
2 x 0.2 A = 0.4 A
Total: 8.75 A
2
for the 5-V litz wires.
2
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