9
D1010-046
- Repeater Power Supply Smart-Hart compatible
G.M. International ISM0066-8
Power Dissipation of D1010-046 Isolators
Section “Technical Data” of D1010-046 isolator specifies the current consumption (maximum current from the nominal power supply, typical 24 Vdc, in normal operation); this data serves
to dimension the current rating of the power supply unit. Section “Technical Data” indicates also the maximum power consumption (maximum power required from the power supply in
the worst (abnormal) operating conditions like for example supply voltage at 30 Vdc, short circuit on the outputs and on the inputs terminals.
The power dissipated
Pd
inside the enclosure for analog signal isolators is:
Pd = Current Consumption (A) * Supply Voltage (V) - Power Dissipated into the input / output loads
Analog signal isolators have higher dissipation than digital signal isolators, in addition 2 channels barriers (D1010D-046) have higher dissipation than single channel units (D1010S-046).
In analog signal isolators each transmitter requires and dissipates 15 V * 0.02 A = 0.3 W. Usually the loads outside the isolator dissipate 1/3 of the total power used.
Isolators are not running at the maximum current all at the same time, the average power consumption of a multitude of isolators can be considered to be only 70 % of the value obtained
from the section “Technical Data”. Considering the 1/3 load power and the 70 % above discussed, the power effectively dissipated internally by the isolators can therefore become ½ of
the actual power delivered by the power supply. Digital barriers dissipate all the supply power inside the enclosure consequently the total power dissipation into a cabinet, with mixed
analog and digital barriers, is determined by the number of channels more than by the number of isolator enclosures. See ISM0075 “Installation in cabinets” for details.
Installation in Cabinet
