GPS-8815C/E
GPS-8815C/E Digital Micro-ohm Meters
1 µΩ resolution · 30 000 counts · four-terminal
A bench micro-ohm meter that reads from a single microhm and sorts at up to 140 readings a second. Those two figures belong to different settings, and the page below is honest about which. Two models: 20 MΩ at 0.05% on the GPS-8815C, 30 kΩ at 0.1% on the GPS-8815E.
Three things that decide the number
Below an ohm the meter is only part of the answer. How long you give the measurement, what the leads contribute, and how warm the part is all move the reading, and all three are yours to set.
Accuracy is bought with measurement time
Two readings a second gives you 0.05%. Twelve gives 0.1%. Thirty-five and above gives 0.5%, and the fastest setting of all blanks the display, because at 140 readings a second nobody is reading it: that rate exists to feed a handler. Pick the rate for the job rather than the headline.
- 2 to 140 readings/s
- 0.05% at the slow rate, 30 000 counts
Four terminals, zeroed on every range
Two terminals drive the current and two sense the voltage, through shielded leads, so the fixture stays out of the reading. A short circuit zero is measured and stored across all ten ranges in a single operation, and wants running again whenever the leads or the clamp change.
- 1 µΩ resolution
- Ten ranges, automatic, held or from a nominal
Corrected to the temperature you name
Resistance moves with temperature, so a winding measured warm reads differently from the same winding cold. Enter the material coefficient, 0.393% per degree for copper, and a reference temperature, and the meter corrects to it over 0 to 80 °C to an accuracy of 0.2 °C.
- 0 to 80 °C at 0.2 °C
- Reading corrected to your reference
Accuracy figures assume 23 °C ±5 °C, 65% relative humidity or less, the correction run, more than 30 minutes warming and a twelve month calibration interval.
Two models, and a real difference
Unlike most pairs in this range, these two are not the same instrument with a different ceiling. The C is faster, more accurate, reaches three decades further and carries the Handler interface. The E is the low-resistance workhorse.
| Model | Range | Basic accuracy | Ranges | Interfaces | Order code |
|---|---|---|---|---|---|
| GPS-8815C | 1 µΩ to 20 MΩ | 0.05% | Ten | RS-232 and Handler | 621555 |
| GPS-8815E | 1 µΩ to 30 kΩ | 0.1% | Seven | RS-232 | 621568 |
If the work is contacts, joints and windings and nothing above 30 kΩ, the GPS-8815E does it. The moment a line, a handler or a resistor above that comes into it, the GPS-8815C is the one.
Ten ranges, and what each one drives
Worth reading rather than skipping. The test current falls by five decades across the range, and the open circuit voltage matters if there is a semiconductor junction anywhere near what you are measuring.
| Range | Accuracy | Resolution | Test current and open circuit |
|---|---|---|---|
| 30 mΩ | 0.1% + 3 digits | 1 µΩ | 670 mA · under 1 V |
| 300 mΩ | 0.05% + 2 digits | 10 µΩ | 670 mA · under 1 V |
| 3 Ω | 0.05% + 2 digits | 100 µΩ | 67 mA · under 1 V |
| 30 Ω | 0.05% + 2 digits | 1 mΩ | 6.7 mA · under 1 V |
| 300 Ω | 0.05% + 2 digits | 10 mΩ | 670 µA · under 5 V |
| 3 kΩ | 0.05% + 2 digits | 100 mΩ | 670 µA · under 5 V |
| 30 kΩ | 0.05% + 2 digits | 1 Ω | 67 µA · under 5 V |
| 300 kΩ | 0.05% + 2 digits | 10 Ω | 6.7 µA · under 5 V |
| 3 MΩ | 0.1% + 5 digits | 100 Ω | Under 3 V |
| 20 MΩ | 0.1% + 5 digits | 1 kΩ | Under 3 V |
Accuracies are for the slow rate, the only one at which the basic figure holds. Medium is 0.1%, and fast, ultra and the display-off rate are 0.5%. Test current is accurate to 10%, and the two highest ranges are driven differently and carry no stated current. Figures are for the GPS-8815C.
Sorting, and telling the line about it
Both of these are on the GPS-8815C. They are what turn a bench instrument into part of a machine.
Thirteen bins, ten of them good
- Set limits as an absolute deviation from a nominal, as a percentage of it, or as sequential upper and lower values.
- A part lands in one of ten pass bins, or reports high, in or low if it falls outside all of them.
- The beeper can sound on the good result or on the bad one, and every bin is available on the Handler.
Opto-isolated, on your supply or ours
Every bin signal and the high, in and low outputs go out through the Handler along with an end of measurement pulse, so the machine knows when the reading is ready rather than guessing. The interface is opto-isolated and will run from its own 5 V or from an external 3.3 to 35 V supply, which is what lets it sit on somebody else’s line without an interface box. External trigger comes in the same way.
An administrator and user account pair, with an optional password, keeps a job that has been set up from being altered by whoever is running it.
Technical specifications
| Measures | DC resistance, four-terminal · GPS-8815C 1 µΩ to 20 MΩ across ten ranges · GPS-8815E 1 µΩ to 30 kΩ across seven |
|---|---|
| Basic accuracy | 0.05% on the GPS-8815C at the slow rate · 0.1% on the GPS-8815E |
| Display | 30 000 counts · reading, deviation, percentage deviation and the sorting result · 3.5 in true-colour TFT · English interface · keypad lock |
| Measurement rate | Slow 2, medium 12, fast 35 and ultra 67 readings per second · a display-off rate of 140 for handler-fed sorting, where the screen blanks |
| Ranging | Automatic, held, or chosen from a nominal value |
| Zero | Short circuit zero, measured and stored across all ranges in one operation |
| Temperature compensation | Range 0 to 80 °C · accuracy 0.2 °C · material coefficient and reference temperature entered on the instrument |
| Sorting | Thirteen bins: ten pass bins with high, in and low · tolerance limits as an absolute deviation or a percentage, or sequential limits · beep on pass, on fail, or off |
| Trigger | Internal, manual, external or bus |
| Interfaces | RS-232 with SCPI, 1200 to 115200 baud, eight bits, no parity, one stop · Handler interface · temperature compensation input · USB to serial adapter available |
| Handler | Bin and high, in and low outputs with an end of measurement signal · opto-isolated · internal 5 V or an external 3.3 to 35 V supply |
| Access | Administrator and user accounts with an optional password |
| Power | 110 or 220 V AC · 48.5 to 62.5 Hz · 20 VA maximum · 1 A slow-blow fuse |
| Environment | Operating 0 to 55 °C · humidity 15% to 85% · altitude to 2000 m · 3.5 kg net |
What’s in the box
- GPS-8815C or GPS-8815E meter
- Four-terminal Kelvin test clip
- RS-232 communication cable
- Acquisition software
- Power cord
- Instruction manual and calibration certificate
C04A cable clamp, ordered separately
A light metal rail with one fixed and one movable clamping head, for the resistance of cable, cord and strip samples 50 to 1000 mm long and 0.1 to 1256 mm² in section. Current connections are rated 100 A and the potential taps come out to 4 mm terminals through low thermoelectric material. A quick-action clamp closes on the sample in one movement, which is what makes the same sample read the same way twice. Part number 902655.