Hypatia Model 307 Complete Specifications, Version 3.2

For SN 0141 and up or upgraded instruments.

15 November 1993, © 1989-1993 Hypatia Inc.

Note: After 15 February 1998, all instruments returned to Hypatia for any reason may receive free accuracy enhancement hardware modifications to improve overall accuracy, yielding better than .25% typical digital accuracy. However, due to the age of these instruments, the formal specifications shown below will not be updated to reflect these advancements at this time. The accuracy data provided in the performance verification certificate supplied with any service can be reviewed to consider your instrument's tighter actual accuracy.


Impedance Measurement:

Accuracy: ± 1% of reading ± 1 digit (Notes 1 & 2)

Range: 0 to 199.9 milliohms

Measurement Technique: True rms conversion of sense voltage divided by true rms conversion of test current independent of phase. Voltage is sensed at the probe's measurement ends by internal probe sense lines or, if Model 109 probes are utilized, by precision Kelvin sensing.

Digital Current Measurement:

Accuracy: ± 1% of reading ± 1 digit (Note 1)

Range: 2.5 to 100 Amps rms (Note 3)

Measurement Technique: True rms conversion of internal precision shunt resistor voltage.

Bar Graph Current Measurement:

Accuracy: ± 1.5% of reading at transition points (every 2.5 Arms) (Note 1)

Range: 2.5 to 77.5 Amps rms (0 to 2.5 Arms implied) (Note 3)

Measurement Technique: True rms conversion of internal precision shunt resistor voltage.

Digital Timer:

Accuracy: ± 1% plus +0, -1 seconds

Range: 1 second to 59 minutes, 59 seconds (Note 4)

Internal Reference: 32.768 KHz crystal controlled time base.

Audio Alert:

When enabled, sounds for any milliohm reading of 100 milliohms or higher.

Accuracy: Logically driven by the digital drive of the main readout. The accuracy therefore exactly matches the accuracy of the impedance measurement.

Operating Duty Cycle:

Continuous to test currents of 35 Amps.

Derate linearly to 50% duty cycle at 50 Amps.

Maximum Cycle Period: 35 to 50 Amps: 4 Minutes

Maximum allowed common mode voltage to ground: 50 Vrms, 71 Vpeak or dc

Maximum normal mode open circuit probe source voltage (at 132 Vrms line voltage): 8.6 Vrms, 12.1 Vpeak

Input Power Requirements:

90 to 132 Volts rms

48 to 66 Hertz sine wave

Maximum Power: 330 Watts (2.5 Arms at 132 Vrms)

Check Resistor:

Resistance: 100 milliohms ± 1%

Maximum continuous current: 17.5 Amps

Verification Schedule:

There are no calibration adjustments, and thus no calibration is required or possible. Complete the formal performance verification procedure annually or following any repair service.


Safety Certification: ETL Listed to UL 1244 (Electrical and electronic measuring and testing equipment)


Operating Temperature Range: 5 to 40°C

Relative Humidity Range: 0 to 90% non-condensing


Mass: 7.7 kilograms (Weight: 17 pounds) {Including two probes}

Overall Dimensions:

Height: 23.27 centimeters (9.16 inches)

Width: 19.89 centimeters (7.83 inches)

Depth: 22.56 centimeters (8.88 inches)

Probe Length, Each Side:

Standard: 1.5 Meters (4.9 feet)

Maximum: 51.0 Meters (167.2 feet) at 50 Amps, 85.0 Meters (278.7 feet) at 40 Amps

Note 1: Test current range: 2.5 to 100 Amps rms (Note 3) Temperature range: 10°C to 40°C

Note 2: Figures exclude contact impedance which adds approximately 1 milliohm with sound double alligator clip type probe connections, and approximately 2 milliohm with one alligator clip and one power connector type probe connections. If the Model 109 Kelvin sense probes are utilized, contact impedance is eliminated.

Note 3: The measurement circuits are broad ranged, but the instrument should not be operated beyond the maximum current limit of 50 Amps or the specified duty cycle limits due to thermal limitations of certain power components.

Note 4: However, one second tests yield a tolerance of +1%, -100% and thus are not advised.

Model 307 Specifications V3.2 , 15 November 1993

© 1989-1993 Hypatia Inc.

Hypatia Inc. Contact Information ucecage@Hypatia.com. Report mail misconduct to uce@ftc.gov.