Calibration procedure for EK-217 (single channel) loop boxes with EKK-217A
calibrator.
Date: 24 September, 2001
Author: Doug Albright
Background
Procedure
Move all data files in the serial numbered subdirectory into a subdirectory created for
this purpose.
Start the EKK-217 program and click on ClrCnfig to reset all variables in the program
to predetermined starting values.
Click on Power Supply Auto Test, then click either Start, or any of the voltage
display buttons to start the auto power supply testing sequence.
1.
The +22V positive test point for the test box is at the top of D8 or D9.
The –22V negative test point for the test box is at the top of D10 and D11.
The +15V test point is at the top of R66.
The –15V test point is at the top of R67.
The +5V reference voltage test point is at the top of R60.
The –5V reference voltage test point is at the top of R61.
No Picture yet…
The +10V raw power supply voltage is measured at one end of the large 75 Ohm end of
the large brown resistor, rearmost on the circuit board. Connect the red lead to one end,
and if it is the same value as the +25V test point, move the connector to the other end.
The +5V meter supply is measured at the special test point loop soldered to the front leg
of the LM7805 voltage regulator.
For the next measurement, plug a BNC to banana test cable from the HP34401A meter
volts, ohms, diode jacks to the Meter VAC BNC jack on the front of the LVDTTool.
Connect the DB-15 test cable from the LVDT connector on the EK-217 to the DB-15
LVDT connector on the LVDTTool.
The software will notice the difference and continue on it’s own.
Measure THD with an instrument designed for this purpose and enter the data values in
the indicated displays. This calibration system does not measure THD…. Yet.
Click on SelfTest to see how far off the LVDT simulator calibration is.
If too far out, click on Calibrate from the Test Select Menu, and tune up the simulator.
To tune the simulator
1. Click on .75VR
2. Click on AvA
3. Press the Local button on the DMM
4. Adjust the leftmost 3.5V trimpot for 3.5V on the DMM. Note theLVDT under the
3.5V pots is lit, indicating which trimpots to adjust.
5. Click on .5VR
6. Adjust the 3V trimpot which is indicated by the illuminated LED.
7. Click on .25VR
8. Adjust the 2.5V trimpot which is indicated by the illuminated LED.
9. Click on .0VR.
10. Adjust the 2V trimpot which is indicated by the illuminated LED.
11. Click on -.25VR
12. Adjust the 1.5V trimpot which is indicated by the illuminated LED.
13. Click on -.5VR
14. Adjust the 1V trimpot which is indicated by the illuminated LED.
15. Click on -.75VR
16. Adjust the .5V trimpot which is indicated by the illuminated LED.
Rerun the SelfTest. If sufficiently trimmed in, click the Save button, then click on the
new data’s filename to see the data set.
Run FullTest to document the As-Received condition of EK-217 signal conditioners.
Make adjustments to the LVDT gain and offset pots if necessary to trim the values in.
Click on 0VR to adjust the Offset pots for both channels A and B.
Click on .5VR to adjust the Gain pot for both channels.
When no further improvements can be made, rerun the FullTest to document the As
Shipped condition.
Click save, then the filename to see the data set.
Click on ITMTest to start torque motor tests.
Move BNC to banana test cord to connect between the Meter mA BNC on the
LVDTTool to the 3A RMS jacks on the HP34401A.
Connect another BNC to BNC cord between the ITM Ext jack on the front of the
LVDTTool to the F.R. Input jack on the front of the ATE-14C.
Set the Mode Switch to Open Loop.
Set the ChB VRU/mA meter to mA.
Click on the 0 Volts button.
Null torque motor current with the setpoint pot.
Check the sweep current high and low endpoint and step size values. If the are
acceptable, Click on the SweepTest button to start the test cycle.
The program will measure torque motor current with the DMM at zero to see if the
absolute value is less than 1 mA. If it is, the test will proceed, else the program will tell
the operator to zero the torque motor and suspend itself. Zero the torque motor current
and click on SweepTest again to restart the torque motor current test.
When the SweepTest starts, the program will:
1. Set 5 volts to the F.R. jack then measure current with the DMM.
2. Measure current with the DMM.
3. Set –5 volts to the F.R. jack then measure current with the DMM.
4. The program determines the full span of current from the 5 volt input, and
computes the scale and offset from F.R. input voltage and torque motor current.
5. The program sets the most negative current value as the SetPoint then:
a. Computes and outputs the DC voltage to the F.R jack to get the specified
torque motor current value.
b. Prompts the operator to enter the value on the torque motor current meter
into the keyboard.
c. When the operator hits the Enter key, the DMM measures torque motor
current.
d. Both values are entered into the lookup table. If the value is in limits, the
background color of the box stays red, if out of limits, the background
color of the display button turns red.
e. The SetPoint is incremented by the StepSize value to get the next SetPoint
value, and the output/measure cycle repeats.
f. The above process continues until the SetPoint exceeds the high current
SetPoint value, then the data set will be saved on the hard drive with a
filename created from the following method. An example filename is
Sn3itm04.c; where:
1. Sn3 indicates the Serial Number of the unit under test.
2. itm indicates this is a torque motor current test. This
number is between 1 and 6, because there were only 6 of
the original ATE-14C test boxes made.
3. 04 is the Test Sequence number from the most recent
LVDT test. This number can range from 1 to 99.
4. .c indicates a CVG data set, .F indicates a FMV data set.
5. 1 is a torque motor current test number. More than one
torque motor data set can be associated with a single LVDT
data set.
After all three data sets have been collected, return to the LVDTForm to setup the data
output display for printing.
1. Click on the LVDT FullTest data file to display the collected LVDTData.
2. Click on the torque motor current data file name to display the torque motor data.
3. Click on the power supply voltage button to select the voltage file.
4. When all data on the display is as desired, click on the Print button to output the
data.
6.
The prob
Adjust the S