Hypatia Models 308 and 309 Performance Verification Procedure

Warning: Potentially lethal line voltages of as much as 132 Volts rms are present on exposed terminals within this instrument. Opening the instrument cabinet is not necessary and is not recommended for the performance verification procedure. If repair service is required but you are unfamiliar with the precautions and techniques necessary for servicing instruments with exposed line voltages, do not attempt to service the instrument yourself. Instead, refer service to appropriately experienced technicians.

Warning: This instrument produces exposed high currents as a normal part of its function. High current shorts through rings, wrist bands or other conductive apparel can cause serious thermal burns which may result in permanent injury. Operators are advised to remove all conductive apparel, especially from the hands and wrists, prior to any operation or service of this instrument.

No Adjustments: There are no hardware adjustments within this instrument. There is no need to open the cabinet to perform a performance verification. If the instrument fails any performance verification step, replacement of the associated components or cleaning of the instrument will be required. Contact Hypatia for service documentation.

Required Probes and Network Cable: Model 109 Kelvin sense probes are required. (If unavailable, they can be easily built: Terminate four conductor telephone type flat cable with a telephone type modular connector on one end and solder all four conductors to a small alligator clip on the other end. A 1.5 meter length is suggested for each probe, but not required.)

Two alligator clip probes (Model 101 or 105) are recommended, but are not required so long as a stout means of attaching two Model 100 series power probes to a power resistor bank and the 100 milliohm cabinet mounted check resistor can be achieved.

One serial network cable with a Mini DIN-8 connector on one end and a suitable serial connector for a Macintosh or a PC on the other end (provided to all customers).

Required Software, Computer, Test Instruments and Fixtures:

Current Model 309 Utility software and Model 309 Operating Software (also used in the model 308)

A 32 bit capable "Wintel" compatible desktop computer with an EIA-232-E (aka RS-232) serial port.

One RMS voltmeter with at least .2% accuracy and at least 1 mV resolution.

One DC voltmeter with at least .04% accuracy and at least 1 mV resolution at 2.50 and 4.096 Vdc.

One digital counter with at least .02% accuracy and a range of at least 16.8 MHz.

One precision power resistor bank, with sense connection points, totaling at least 100 milliohm with at least .2% accuracy, and with taps if verification at readings of less than 100 milliohm are desired. This resistor bank must have a current handling capacity at least meeting the capacity and duty cycle limits of the Models 308 and 309.

Step by Step Procedure:

1. Using the Model 309 Utility software, install the latest version of the Model 309 Operating Software into the instrument (the Model 309 Operating Software is also used in the Model 308). This software is available free on the web at www.Hypatia.com. If necessary see the owner's manual for installation instructions, also on the web. Note: Installation of the latest Operating Software is mandatory - no exceptions. These are safety mission instruments. Failure to install the latest Operating Software is negligent and may create a serious legal liability. Hypatia specifically prohibits certification of instruments using any obsolete version of the Operating Software, and does not warrant the accuracy or performance of any instrument so serviced. Hypatia promptly reports third party service quality failures to instrument owners whenever we become aware of them.

2. Set the Model 309 "main power" switch to the off position. Rotate the "current adjust" knob to its full counter clockwise position.

3. Connect an IEC power cord to the rear panel IEC receptacle of the Model 309 and to a power source meeting the specifications printed above the IEC receptacle.

4. Set the Model 309 "main power" switch to the on position and allow five minutes to establish near thermal equilibrium.

5. Secure two Model 100 series power probes, preferably alligator clip types (Model 101 or 105), to the front panel connectors of the instrument as described in the operation section of the manual, but leave the modular connectors unconnected. Connect the Kelvin sense probes (Model 109) to the modular receptacles. Connect the power probe ends to a 100 milliohm precision power load. Connect the Kelvin sense probe ends to the sense taps of the precision load, being certain that the right Kelvin sense line is connected to the same side of the load as the right power probe, and similarly for the left sense line and probe. Verify that the Kelvin connectors do not directly physically touch the power probe connectors.

6. Set the main readout to the milliohm mode. If enabled, disable the test timer and all alarms.

7. Push the "start test" switch, then slowly increase the test current to 2.5 Amps. Record the Model 309 impedance reading. Repeat for 10.0, 17.5, 25, 30 and 60 Amps. Perform the 60 Amp test quickly so as not to violate duty cycle limits. Push the "start test" switch again to stop the test. Rotate the "current adjust" knob to its full counter clockwise position. Compare the results to specifications.

8. If impedance measurement performance checks for load values other than 100 milliohms are desired, repeat step six for each value.

9. If altered, reset the load bank to 100 milliohms. Connect an RMS voltmeter to the sense taps of the precision load. Set the Model 309 main readout to the current mode.

10. Push the "start test" switch, then slowly increase the test current until the RMS voltmeter reads 250 mV, which equates to 2.5 Amps. Record the Model 309 digital current reading. Vary the current adjust knob slightly to confirm that bar graph threshold crossing matches the digital reading. Repeat for 10.0, 17.5, 25, 30 and 60 Amps. Perform the 60 Amp test quickly so as not to violate duty cycle limits. Push the "start test" switch again to stop the test. Rotate the "current adjust" knob to its full counter clockwise position. Compare the results to specifications.

11. Set the Model 309 main readout back to the milliohm mode. Establish a connection between the probe's measurement ends and the 100 milliohm check resistor on the back of the instrument. Use the Kelvin sense lines, being certain that the right Kelvin sense line is connected to the same side of the 100 milliohm resistor as the right power probe, and similarly for the left sense line and probe. Verify that the Kelvin connectors do not directly physically touch the power probe connectors.

12. Push the "start test" switch and rotate the "current adjust" knob clockwise until a current of 2.5 Amps is reached. Record the impedance reading. Push the "start test" switch again to stop the test. Rotate the "current adjust" knob to its full counter clockwise position. Compare the reading to the Model 309's reading of the 100 milliohm precision load taken earlier at 2.5 Amps to determine the value of the cabinet mounted check resistor by error subtraction. The result should be 100 milliohms ± 1%.

13. [This step not applicable to the Model 308.] Check operation of the milliohm, high current and low current alarms. The set points of the alarms may be reviewed (and changed if necessary) by cycling through the adjust menu ("adjust select" button). Execute tests which exceed each alarm's threshold and verify that an audio alert sounds and the associated alarm light flashes. Stop the last test and rotate the "current adjust" knob to its full counter clockwise position.

14. Remove all of the probes except the left Kelvin sense probe from the Model 309. Turn the Model 309 on its side and note the two probe ports on the bottom near the front of the instrument.

15. Connect the reference terminal of a DC voltmeter to the alligator clip end of the left Kelvin sense probe. Insert the other voltmeter probe into the probe port marked "2.500 V" or "4.096 V". Compare the reading to the ideal of 2.500 V or 4.096 V (2E12 mV) and verify that accuracy is within .2%.

16. Connect the reference terminal of a digital counter to the alligator clip end of the left Kelvin sense probe. Insert the other counter probe into the probe port marked "16.777 MHz". Compare the reading to the ideal of 16.777216 MHz (2E24 Hz) and verify that accuracy is within .1%.

17. Set the "main power" switch to the off position, turn the Model 309 to its normal, upright position, and remove the left Kelvin sense probe and the power cord from the instrument.

18. Check that the two lower rear #15 torx screws which secure the top cabinet half are tight and that there is a lockwasher located between the cabinet halves on these screws to insure proper grounding of the upper cabinet half. The edges of the lockwashers are visible from the bottom of the instrument.

This Completes the Performance Verification Procedure.