13 - 3
13. CHARACTERISTICS
(2) Heat dissipation area for enclos ed servo amplifier
The enclosed control box (hereafter called the control box) which will contain the servo amplifier
should be designed to ensure that its temperature rise is within 10 (50 ) at the ambient
temperature of 40 (104 ). (With a 5 (41 ) safety margin, the system should operate within a
maximum 55 (131 ) limit.) The necessary e nclosure heat dissipation area can be calculated by
Equation 13.1.
P
A
K
T.............................................................................................................................................(13.1)
where, A : Heat dis sipation area [m2]
P : Loss generated in the control box [W]
T : Diff erence between internal and ambient temperatures [ ]
K : Heat dissipation coefficient [5 to 6]
When calculating the heat dissipation area with E quation 13.1, assume that P is the sum of all losses
generated in the enclosure. Refer to Table 13.1 for heat generated by the servo amplifie r. "A" indicates
the effective area for heat dissipation, but if the enclosure is directly installed on an insulated wall,
that extra amount must be added to the enclosure's surface area.
The required heat dissipation area will vary wit the conditions in the enclosure. If convection in the
enclosure is poor and heat builds up, effective heat dissipation will not be possible. Therefore,
arrangement of the equipment in the enclosure and the use of a cooling fan should be considered.
Table 13.1 lists the enclosure dissipation area for each servo amplifier when the servo amplifier is
operated at the ambient temperature of 40 (104 ) under rated load.
(Outside) (Inside)
Air flow
Fig. 13.2 Temperature distribution in enclosure
When air flows along the outer wall of the enclosure, effective heat exchange will be possible, because
the temperature slope inside and outside the enclosure will be steeper.