Calculation Of External Wiring Resistance - Hitachi HIDIC EH-150 Instruction Manual

12. Appendix

12.1 Calculation of External Wiring Resistance

Assuming that the cross section and length of tinned annealed copper wire are S(mm
R(ohm) of the wire is
R ≈ 0.01854×L / S
For example, for a cable whose cross section is 0.18 mm
R ≈ 0.01854×200 / 0.18=20.6 ohm
Because the current terminal of EH-PT4 doubles in both ways, the resistance also doubles 20.6 ohm×2 = 41.2
ohm.
Because this resistance is the value when the ambient temperature around the wire is 20°C, if the ambient
temperature is over 20°C, the resistance rises.
The rise per 1°C is about 0.4%.
In case the ambient temperature is 40°C, the resistance is
R = 41.2×(1+0.004(40-20))
≈ 44.5 ohm
Concerning the details of resistance, investigate individually for each wire. It may be slightly different from the
calculated value.
Reference
In the case of Hitachi twisted shielded cable (CO-DS-IREVV-SX,(10 pairs to 52)),the maximum conductor
resistance in the cross section of 0.18mm
Hitachi's Guide Book).
2
and length is 200 m, the resistance is
2
under the temperature 20
12-1
12. Appendix
2
), and L(m), the resistance
°C
is 121.5 ohm/ (according to