Mitsubishi Electric MELSERVO-J4 MR-J4 A Series Instruction Manual page 259

10. CHARACTERISTICS
(2) Heat dissipation area for an enclosed type cabinet
The enclosed type cabinet (hereafter called the cabinet) which will contain the servo amplifier should be
designed to ensure that its temperature rise is within +10 C at the ambient temperature of 40 C. (With
an approximately 5 C safety margin, the system should operate within a maximum 55 C limit.) The
necessary cabinet heat dissipation area can be calculated by equation 10.1.
P
A = ·········································································································································· (10.1)
K • T
A : Heat dissipation area [m
P : Loss generated in the cabinet [W]
T : Difference between internal and ambient temperatures [ C]
K : Heat dissipation coefficient [5 to 6]
When calculating the heat dissipation area with equation 10.1, assume that P is the sum of all losses
generated in the cabinet. Refer to table 10.1 for heat generated by the servo amplifier. "A" indicates the
effective area for heat dissipation, but if the cabinet is directly installed on an insulated wall, that extra
amount must be added to the cabinet's surface area. The required heat dissipation area will vary with
the conditions in the cabinet. If convection in the cabinet is poor and heat builds up, effective heat
dissipation will not be possible. Therefore, arrangement of the equipment in the cabinet and the use of a
cooling fan should be considered. Table 10.1 lists the cabinet dissipation area for each servo amplifier
(guideline) when the servo amplifier is operated at the ambient temperature of 40 C under rated load.
When air flows along the outer wall of the cabinet, effective heat exchange will be possible, because the
temperature slope inside and outside the cabinet will be steeper.
2
]
(Outside the cabinet)
Fig. 10.2 Temperature distribution in an enclosed type cabinet
(Inside the cabinet)
Air flow
10 - 4