41
83507013 Rev G
Cross sect. area
(mm²)
Resistivity
OHM/Km
Maximum length in meters to limit
voltage drop to 1V or less
5A
10A
20A
50A
150A
2.5
8.21
24.0
12.0
6.0
2.4
0.8
4
5.09
39.2
18.6
9.8
4.0
1.4
6
3.39
59.0
29.4
14.8
5.8
2.0
10
1.95
102.6
51.2
25.6
10.2
3.4
16
1.24
160.0
80.0
40.0
16.0
5.4
25
0.795
250.0
125.0
62.0
25.2
8.4
35
0.565
354.0
177.0
88.0
35.4
11.8
Table 3-3: Maximum Wire Length for 1 V Drop on Lead (in meters)
For currents not shown in Table 3-2 and 3-3, use the formula:
Maximum length=1000/(current x resistivity)
Where current is expressed in Amperes and resistivity in ohms/km or ohms/1000ft.
3.9.3 Wire Termination
The wires should be properly terminated with terminals securely attached. DO NOT use
unterminated wires for load connection at the power supply.
CAUTION
When local sensing, a short from +LS or +S to -V or -S or -LS, will cause damage
to the power supply. Reversing the sense wires might cause damage to the power
supply in local and remote sensing. (Do not connect -S to +V or +S to -V).
3.9.4 Noise and Impedance Effects
To minimize the noise pickup or radiation, the load wires and remote sense wires should
be twisted pairs to the shortest possible length. Shielding of sense leads may be
necessary in high noise environments. Where shielding is used, connect the shield to
the chassis via a rear panel Ground screw. Even if noise is not a concern, the load and
remote sense wires should be twisted-pairs to reduce coupling, which might impact the
stability of power supply. The sense leads should be separated from the power leads.
Twisting the load wires reduces the parasitic inductance of the cable, which could
produce high frequency voltage spikes at the load and the output of the power supply,
because of current variation in the load itself.
The impedance introduced between the power supply output and the load could make
the ripple and noise at the load worse than the noise at the power supply rear panel
output. Additional filtering with bypass capacitors at the load terminals may be required
to bypass the high frequency load current.
3.9.5 Inductive Loads
Inductive loads can produce voltage spikes that may be harmful to the power supply. A
diode should be connected across the output. The diode voltage and current rating
should be greater than the power supply maximum output voltage and current rating.
Connect the cathode to the positive output and the anode to the negative output of the
power supply.
Where positive load transients such as back EMF from a motor may occur, connect a
surge suppressor across the output to protect the power supply. The breakdown voltage
rating of the suppressor must be approximately 10% higher than the maximum output
voltage of the power supply.
