Air Cooled Data Processor With Blower Motor Controlled by Variable Frequency Source to Reduce Noise When Cooling Load is Low
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
In this data processor, the blowers for air cooling have sufficient capacity for adverse conditions of temperature, coo load, and altitude, as is conventional, and it also has a variable frequency digital control that controls the frequency of the power which drives the blower motors. The motors operate at the minimum speed that produces adequate cooling. Preferably, the control converts a commercial power supply of 50 or 60 hertz to power the blowers in a range of 47 to 63 hertz. Therefore, when the blowers are providing just adequate cooling, the motor speed corresponds to an input frequency of 47 hertz. Under adverse conditions, the motor speed can increase to 63 hertz. The normal operating condition therefore produces a noise level which is approximately 6 decibels below the extreme condition which is rare.