From: Bellomo, Paul
Sent: Wednesday, September 21, 2005 12:53 PM
To: MacNair, Dave; de Lira, Antonio C; Emma, Paul J.
Cc: Schultz, David C.; Luchini, Kristi; Fuller, Robert W.
Subject: RE: Measurements of Elgar 33A 30V Power Supply Stability

Attachments: DCS33 Temp Stability.pdf

Dave MacNair:

 

Nice job. This data will be very useful to help resolve the LINAC QE magnet operational issues.

 

Paul Bellomo

Stanford Linear Accelerator Center, MS 49

2575 Sand Hill Road

Menlo Park, CA 94025

Office:  650-926-2342

Cell:    925-963-0314

On Star: 925-785-8199

bellomo@slac.stanford.edu  

 

 

-----Original Message-----
From: MacNair, Dave 
Sent: Wednesday, September 21, 2005 11:09 AM
To: Bellomo, Paul; de Lira, Antonio C; Emma, Paul J.
Subject: Measurements of Elgar 33A 30V Power Supply Stability

 

I measured the stability of the Elgar 33A/30V in current mode over a 5 to 45 degree C range. These units have isolated inputs and outputs. These is necessary for the boost power supplies that do not operate at ground potential.

 

I have attached a copy of the output current measured using a independent transductor. The temperature coefficient of the unit can be estimated as follows;

 

(67 PPM of I)/deg C + (8 PPM of FS)/deg C

 

I  = operating current

FS = full scale current (33 amps)

 

At 33 amps, the unit has a temperature coefficient of about 75PPM/deg C. At 1 amp the unit has a temperature coefficient of about 330 PPM/deg C.

 

For a 30 degree C change, the expected relative change in current would be the following;

 

33 amps  0.22%

10 amps  0.28%

 3 amps  0.46%

 1 amp   0.99%

 

These drifts do not include the drift of the DAC and ADC cards. These should be small relative to the drift of the power supply.

 

The supplies will meet the 0.5% stability specification for the quad magnets if we operate the supplies at more then 10% of its full scale rating. Where the magnet operates at less then 3 amps, we should use a smaller power supply.