Kikusui PAD-L III Series, Operation Manual

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3-8 Basic Operation PAD-L
3.3 Connecting load
This section describes the cables (load cables) connecting the unit and a load and the
proper procedure for connecting loads to the output terminals.
3.3.1 load cables
WARNING
• For load cables, use cables that have sufficient current capacity
with respect to the rated output current of the unit and that have
sufficient withstand voltage with respect to the isolation voltage
of the unit.
Current capacity of load cables
Load cables must be rated to carry the maximum rated output current of the unit. If
their current rating exceeds the maximum rated output current, they will carry the
maximum current even if a load is short circuited.
The allowable current of a wire is determined by the maximum allowable
temperature of the cable insulation, which in turn is governed by a current-caused
resistance loss, ambient temperature, and thermal resistance to the outside. The
allowable currents in Table 3-1 show the capacity of current flowing through a heat-
resistant PVC wire (single wire) having a maximum allowable temperature of 60
°
C
when the wire is stretched horizontally in the air at an ambient temperature of 30
°
C.
If the condition is such that PVC wires with lower heat-resistant temperature are
used, ambient temperature reaches more than 30
°
C, or the wires are bundled,
resulting in low heat radiation, the current capacity needs to be reduced.
Based on this consideration, it is better to make heat radiation as great as possible to
let a larger current flow, as long as wires having the same heat-resistant temperature
are used. For measures against noise in the load cables, installing the + (pos.) and -
(neg.) output lines side by side or bundling them together is more effective against
unnecessary noise. The Kikusui-recommended currents shown in Table 3-1 are
allowable current values that have been reduced in consideration of potential
bundling of load cables. Use these values as a guideline when installing load wires.
Because wires have resistance, voltage drop in wires becomes greater as the wire
becomes longer or the current becomes larger. This causes the voltage applied at the
load end to be smaller. The PAD-L series power supplies have a sensing function
that compensates for this voltage drop. Compensation of up to approximately 1.2 V
is available for a single line. If voltage drop exceeds this level, wires having a greater
sectional area should be used.