LASER INTERFEROMETER GRAVITATIONAL WAVE OBSERVATORY
LIGO Laboratory / LIGO Scientific Collaboration
LIGO- T00000000-00-C
Document Type
March, 2007
Test Procedure and Results
DCC Number
LIGO – T070071-00-C
March
March 28, 2007
ISI Coarse and Fine Driver Module/Chassis Test Procedure
Mohana Mageswaran
Distribution of this document:
LIGO Science Collaboration
LIGO Laboratory
This is an internal working note of the LIGO Project.
California Institute of Technology
LIGO Project – MS 18-34
1200 E. California Blvd.
Pasadena, CA 91125
Phone (626) 395-2129
Fax (626) 304-9834
E-mail: info@ligo.caltech.edu
Massachusetts Institute of Technology
LIGO Project – NW17-161
175 Albany St
Cambridge, MA 02139
Phone (617) 253-4824
Fax (617) 253-7014
E-mail: info@ligo.mit.edu
LIGO Hanford Observatory
P.O. Box 1970
Mail Stop S9-02
Richland WA 99352
Phone 509-372-8106
Fax 509-372-8137
LIGO Livingston Observatory
P.O. Box 940
Livingston, LA 70754
Phone 225-686-3100
Fax 225-686-7189
http://www.ligo.caltech.edu
LIGO- T070071-00-C
Tech: __________________
Date: __________________
1. Overview The Coarse and Fine Driver chassis consists of 4 driver modules. Coarse is capable of supplying
+/- 3.47 amps DC into 4.3 ohms maximum, and Fine is capable of supplying +/-1.45 amps DC into
9.3 ohms maximum when powered from the maximum allowed power supply of +/-24VDC.
This procedure covers the test of the chassis as a whole and each of the four driver modules
contained within the chassis.
2. Test Equipment •
Power Supply capable of at least +/-10 amps
•
Dynamic Signal Analyzer SR785
•
Multi meter
•
Oscilloscope
•
Function Generator
•
Loads 5 ohm, 50 watt resistor and 10 ohms, 20 watt resistor
3. Preliminaries •
Set the power supplies to +/-24 volts, turn them off then connect to chassis under test
•
Connect the +24V/-24V to the chassis DC IN Connector.
•
Connect the 5 Ohms loads to Coarse 1 Out & Coarse 2 Out, and the 10 Ohms loads to Fine
1 Out & Fine 2 Out.
4. DC Tests •
Turn on the power supplies to the chassis under test and record the total current. The
specification assumes all 4 modules are installed, otherwise note the configuration in the
chart.
Total Current
Specification
Measured Current
+24 Volts
-24 Volts
2
LIGO- T070071-00-C
Tech: __________________
Date: __________________
•
Record the output offset voltage of each driver module in the chassis as measured at
TP25.
Module
Fine 1
Coarse 1
Fine 2
Coarse 2
Offset Voltage
(0 to +/-10 mV)
•
Verify airflow direction (front panel inlet, rear panel outlet) for each of the two cooling
fans, and that each fan is running at approximately the same speed.
Airflow Checked
5. Current Limit Tests The following tests are sequentially performed to each of the 4 individual modules. Each module is
fuse protected at 15 amps of output current.
•
Connect the 5 ohm power resistor to Coarse1 Out, Coarse2 Out and 10 ohm power
resistor to Fine1 Out, Fine2 Out of the Chassis under test.
•
Apply DC input (approximately 0 to 12 volts) to the test points TP4 and TP11 on the
test board(D060504) and slowly increase the input voltage while monitoring the power
supply current for evidence of current limiting (increase input voltage with no increase
in power supply current)
•
Repeat for the other polarity of input voltage and record all data in table below
Module
Fine 1
Coarse 1
Fine 2
Coarse 2
Positive
Current
Limit (10 +/- 1
amps)
Negative
Current
Limit (10 +/- 1
amps)
3
LIGO- T070071-00-C
Tech: __________________
Date: __________________
6. Frequency Response Tests •
Set the dynamic signal analyzer for a 0.1 Hz to 1 KHz swept sine measurement with an
input drive level of 1 volt p-p
•
Sequentially measure the frequency response of each module according to the data table
below
Module
Fine 1
Coarse 1
Fine 2
Coarse 2
10 Hz Gain
Pole location
(~0.4 Hz)
Zero location
(~15.9 Hz)
7. Current and Voltage Monitor Measurement (A)
Input
Output
Calculated
Measured
Vmon / Imon
J7 1 & 6 - 1VDC
TP18 & TP20
-2.00 VDC / 200 mA
J7 2& 7 - 1VDC
TP18 & TP20
-2.00 VDC / 100 mA
J7 3 & 8 - 1VDC
TP18 & TP20
-2.00 VDC / 100 mA
J7 4 & 9 - 1VDC
TP18 & TP20
-2.00 VDC / 200 mA
(B)
After taking the measurements check with the oscilloscope for no oscillations at the output test
point TP25.
4
LIGO- T070071-00-C
Tech: __________________
Date: __________________
8. Output Noise Measurements The output noise voltage of each coil driver should be measured using the dynamic signal analyzer
SR785. This measurement should be made directly to the output of the coil driver at TP25.
Module
Fine 1
Nominal Noise
Freq > 30 Hz
30 nV/rtHz
10 Hz < Freq < 30 Hz
80 nV/rtHz
1 Hz < Freq < 10 Hz
450 nV/rtHz
Freq < 1 Hz
Coarse 1
Fine 2
(450 nV/rtHz)*(1/freq)
N/A
Freq > 30 Hz
30 nV/rtHz
10 Hz < Freq < 30 Hz
80 nV/rtHz
1 Hz < Freq < 10 Hz
450 nV/rtHz
Freq < 1 Hz
Coarse 2
Actual Noise
(450 nV/rtHz)*(1/freq)
N/A
5