U S E R RESPONSIBLE F O R V E R I F Y I N G VERSION A N D COMPLETENESS
O E M F U N C T I O N A L S P E C I F I C A T I O N U L T R A S T A R X P ( D F H C ) SSA M O D E L S 1.12/2.25 G B - 1.0" H I G H
Example 4. Calculate the 12 volt peak current.
T o compute the sum of the 12 volt peak currents the following is done.
| mean |
|
+ 1 2 V D C (idle avg) | 0.41 | amps |
+ 1 2 V D C (seek peak) | 1.20 | amps |
T O T A L | 1.61 | amps |
Example 5. Calculate the mean plus 3 sigma 12 volt peak current.
T o compute the sum of the 12 volt peak current's 1 sigma value assume all distributions are normal. There- fore the square root of the sum of the squares calculation applies.
| sigma |
+ 1 2 V D C (idle avg) | 0.03 amps |
+ 1 2 V D C (seek peak) | 0.02 amps |
T O T A L sqrt((0.03)**2+(0.02)**2)=0.036 amps
So the mean plus 3 sigma peak current is 1.61 + 3*0.036= 1.72 amps
Things to check when measuring 12 V supply current:
Null the current probe frequently. Be sure to let it warm up.
Adjust the power supply to 12.00 V at the drive terminals.
Use a proper window width, covering an integral number of spindle revolutions.
Measure values at 25 degree C casting temperature.
Get a reliable trigger for Seek Peak readings.
Source filename=POWER | I B M Corporation | Page 23 of 87 |