The
data sheet states:
Maximum continuous current draw must be no more than 1.5A per fan connector, no more than 6A total. Pulsed current may be up to 5A per connector, the pulse width must be less than 50mS. This pulse specification allows for the fan’s start-up current spike.
1.5 amps x 12 volts = 18 watts per connector (so two of your 7-watt fans per connector would be the maximum safe number).
We test each unit with four a 92mm Delta FFB0912EHE fans rated at 1.5 amps each.
Please make sure your power supply can handle the load on its +12v before connecting a huge numbers of fans.
You need to go from the fans
rated power, not from the current you measure. That will give some room for worst-case conditions.
At power-on fans are started up with a 0.5 second delay between each fan so the peak currents do not all happen at once.
The fan power can be stored in the 633's EEPROM so the fans come on automatically at a pre-selected power setting.
Multiple fans will not be able to have tach inputs read. One per fan's tach per 633 connector still can be read, but the others will have to be 2-wire fans or have their tach signal disconnected.
