6. LOADING AND INSTALLATION
Power consumption of output circuits (with an average number of points
WOUT = lout x Vdrop x average number of outputs on at one time
= output current (actual operating current) (A)
Vdrop = voltage dropped across each output load
Power consumption of input circuits (with an average number of points
WIN = liN
E x average number of inputs on at one time
input current (effective value for AC) (A)
E = input voltage (actual operating voltage) (V)
Power consumption of the special function unit power supply is ex-
Ws = 124v x 24
1100V x 100 (W)
The sum of the above values is the power consumption of the entire PC
Further calculations are necessary to work out the power dissipated by
the other equipment in the panel.
Generally temperature rise in the panel is expressed as;
where, W : power consumption of the entire PC system
(obtained as above)
panel inside surface area (m 2)
if the panel temperature is controlled by a fan, etc.
if panel: air is not circulated.
Fans, heat exchangers of cooling units must be installed if the panel
temperature is likely to exceed 55°C.
Fans should be fitted with suitable filters and guards.