GPS-276 / GPS-278
GPS-276 & GPS-278 AC/DC Clamp Meters with Inrush
1000 A true RMS · or 2000 A and 2000 V · 80 ms inrush capture
Two clamp meters for two different jobs. The GPS-276 is the general purpose instrument: 1000 A through a 52 mm jaw, true RMS on AC current and AC voltage, and a full meter behind it with temperature and frequency. The GPS-278 is the one you buy when the current or the voltage is bigger than that: 2000 A through a 55 mm jaw and 2000 V on the leads, with a simpler meter behind it.
GPS-276 · 1000 A, true RMS AC and DC
Which model?
Not a ladder. The higher model number is not the better meter. The GPS-276 does more, and does it with true RMS on both AC paths; the GPS-278 reaches further, and gives up temperature, frequency, display resolution and the rotary switch to do it. Choose by the biggest number you need to measure.
The work is under 1000 A and 1000 V
Which is most installation, HVAC, drive and maintenance work.
- True RMS on AC current as well as AC voltage, so drives and distorted loads read right
- Temperature to 1000 °C on the supplied probe, frequency to 40 MHz with duty cycle
- 3999 count display and a rotary switch
- Capacitance to 10 mF, resistance to 40 MΩ
- Smaller and lighter: 249 mm and 360 g
The current or the voltage exceeds that
Switchgear, busbar, traction and heavy DC, where a general purpose clamp runs out.
- 2000 A AC and DC through a 55 mm jaw
- 2000 V AC and DC on the test leads
- True RMS on AC voltage; AC current is average responding, calibrated to a sine
- Inrush capture in manual range, so select 2000 A first if the magnitude is unknown
- Function keys instead of a rotary switch, which keeps the case narrow for a jaw this size
| What decides it | GPS-276 | GPS-278 |
|---|---|---|
| Current | 40 / 400 / 1000 A, AC and DC | 20 / 200 / 2000 A, AC and DC |
| Voltage | To 1000 V DC, 700 V AC | To 2000 V DC and AC |
| AC current response | True RMS | Average responding, sine calibrated |
| AC voltage response | True RMS | True RMS |
| Jaw | 52 mm | 55 mm |
| Display | 3999 count | 1999 count |
| Frequency | 100 Hz to 40 MHz, plus duty cycle | — |
| Temperature | −50 to 1000 °C, probe supplied | — |
| Inrush | True RMS over 80 ms | RMS over 80 ms, manual range only |
| Controls | Rotary switch | Function keys, no rotary switch |
| Measurement category | CAT II 1000 V, IEC 61010-1 | CAT II 1000 V, IEC 61010-1 |
| Part number | 622276 | 622278 |
Measurement capability
A clamp reads current from outside the insulation, with nothing disconnected and nothing in series. On both of these the starting current is captured as an 80 millisecond RMS window, which is what a motor start looks like, and a starting current you can put a number to is the difference between sizing a protection device and guessing at one.
52 mm and 55 mm jaws
Both take the cable sizes found on distribution boards and motor feeds. The GPS-278 jaw opens 3 mm further and carries twice the current.
True RMS where it counts
The GPS-276 measures AC voltage and AC current true RMS. The GPS-278 measures AC voltage true RMS and AC current average responding, calibrated to a sine.
Inrush over 80 ms
Both capture the RMS of an 80 millisecond window rather than a peak, which is the shape a motor or compressor start actually has.
DC current with zero
Both measure DC current through the jaw and null the reading first. Zero in the orientation you will measure in; the earth’s field moves it otherwise.
Temperature and frequency
The GPS-276 reads −50 to 1000 °C on the supplied K type bead and counts frequency to 40 MHz with duty cycle. The GPS-278 has neither.
2000 V on the leads
The GPS-278 measures AC and DC voltage to 2000 V, twice the GPS-276, for distribution and traction work where 1000 V is not enough headroom.
Technical specifications
| Specification | GPS-276 | GPS-278 |
|---|---|---|
| Display | 3999 counts, backlit, clamp head light | 1999 counts, backlit, clamp head light |
| Jaw opening | 52 mm, single conductor | 55 mm, single conductor |
| AC current | 40 / 400 / 1000 A · ±(2% + 10) on 40 A · 10 mA resolution · true RMS, 50 to 60 Hz | 20 / 200 / 2000 A · ±(1.9% + 10) · 10 mA resolution · average responding, 50 to 60 Hz, no reading below 0.3 A |
| DC current | 40 / 400 / 1000 A · ±(2% + 10) on 40 A · 10 mA resolution · zero key | 20 / 200 / 2000 A · ±(1.9% + 10) · 10 mA resolution · zero key |
| Inrush current | True RMS of an 80 ms window, on the AC current ranges | RMS of an 80 ms window, manual range only |
| DC voltage | 400 mV to 1000 V · ±(0.8% + 2) · 0.1 mV resolution | 2 V to 2000 V · ±(0.5% + 5) · 1 mV resolution |
| AC voltage | 400 mV to 700 V · ±(1.2% + 5) · 0.1 mV resolution · true RMS, 10 Hz to 1 kHz | 2 V to 2000 V · ±(0.8% + 5) · 1 mV resolution · true RMS, 40 Hz to 1 kHz |
| Resistance | 400 Ω to 40 MΩ · ±(1% + 3) · 0.1 Ω resolution | 200 Ω to 20 MΩ · ±(0.8% + 5) · 0.1 Ω resolution |
| Capacitance | 10 nF to 10 mF · ±(3% + 20) on 10 nF · 1 pF resolution | 20 nF to 2000 µF · ±(3% + 10) · 10 pF resolution · automatic ranging only |
| Frequency | 100 Hz to 40 MHz · ±(0.5% + 3) · 1 V rms sensitivity | — |
| Duty cycle | 1% to 99% · ±(0.5% + 3) | — |
| Temperature | −50 to 1000 °C · ±1% ±5 to 300 °C · K type bead supplied | — |
| Diode | Forward voltage, 1.5 mA test current | Forward voltage, 0.5 mA test current |
| Continuity | Buzzer below 90 ±20 Ω | Buzzer below about 60 Ω |
| Ranging | Automatic, manual override on volts, current and resistance | Automatic, manual override on volts, current and resistance |
| Controls | Rotary switch | Function keys; functions step round on the power key |
| Data hold · auto power off | Yes · after 10 minutes, can be defeated at switch-on | Yes · sleeps after 10 minutes, woken on the power key |
| Overload protection | 1000 V DC or AC peak on volts · 250 V rms on mV, capacitance, frequency, duty and temperature · 220 V rms on resistance | 2000 V DC or AC peak on volts · 220 V rms on resistance, capacitance, diode and continuity |
| Compliance | IEC 61010-1 · CAT II 1000 V · CE | IEC 61010-1 · CAT II 1000 V · CE |
| Power | 1 × 9 V battery | 1 × 9 V battery |
| Operating environment | 0 to 40 °C, below 75% RH | 0 to 40 °C, below 75% RH |
| Dimensions (h × w × d) | 249 × 89 × 38 mm | 270 × 100 × 46 mm |
| Weight | About 360 g with battery | About 460 g with battery |
Where they are used
Air conditioning and refrigeration
Compressor starting current, capacitor checks and temperature on the GPS-276, most of a service kit in one hand.
Variable frequency drives
Drive supplies and distorted loads, where the GPS-276’s true RMS current path gives the right number.
Electroplating and DC welding
Heavy DC current on both models; the GPS-278 for anything past 1000 A.
Switchgear and busbar
The GPS-278 reads to 2000 A through a 55 mm jaw where a general purpose clamp runs out of range.
Traction and heavy DC installations
Battery, rectifier and traction circuits to 2000 A and 2000 V DC on the GPS-278.
Plant and installation maintenance
Both are full meters behind the jaw: volts, resistance, capacitance, diode and continuity.
What’s in the box
- Clamp meter, model as ordered
- Test lead set
- K type temperature probe, GPS-276 only
- 9 V battery
- Carrying case
- Operation manual
Before you order
The GPS-278 measures AC current average responding, not true RMS, and shows nothing below 0.3 A; its inrush function works in manual range only, and above 1000 A it should not measure continuously for more than five minutes. Both models are rated CAT II 1000 V to IEC 61010-1: the category describes the transient environment the instrument is built to survive, not a measurement range, and the GPS-278’s 2000 V ranges do not change it. On both, zero the DC current range in the orientation you will measure in, clamp a single conductor only, and take the test leads out before measuring current. AC current accuracy on both is specified at 50 to 60 Hz.
Compliance and downloads
Safety and approvals
- Overload
- GPS-276: 1000 V DC or AC peak on volts. GPS-278: 2000 V DC or AC peak on volts. 220 V rms on resistance on both
- Pollution
- Degree 2
- Warranty
- 1 year, subject to product registration with GPS LTD
- Calibration
- Service and calibration available; one-year calibration interval