Earth resistance up to 9999 Ω with 3-pole and 2-pole methods
AMRU-10
Earth resistance meters
AMRU-10
Earth resistance meter
Earth resistance by the technical 3-pole and the 2-pole methods, up to 9999 Ω, in an IP67 housing.
Grounding, kept simple
The AMRU-10 measures earth resistance by the technical three-pole method per EN 61557-5 — from 0.53 Ω to 9999 Ω at 50 V — and by the two-pole method, along with the resistance of the auxiliary electrodes RH and RS up to 19.9 kΩ and interference voltages up to 100 V. Its ergonomic, rugged housing and large, legible display make it a natural choice for field work.
Stable readings under disturbance
A measurement current above 20 mA at 125 or 150 Hz and a selectable test voltage of 25 or 50 V keep the readings accurate even with disturbance voltages up to 24 V present. Resolution starts at 0.01 Ω with an intrinsic uncertainty of ±(3 % of reading + 3 digits), and battery indication with automatic power-off looks after the four AA cells.
Main features
- Technical 3-pole method per EN 61557-5 and 2-pole method.
- Auxiliary electrode resistances RH and RS up to 19.9 kΩ.
- Interference voltage measurement up to 100 V.
- Selectable measuring voltage of 25 V or 50 V.
- Battery state indication and auto-off function.
- CAT III 300 V safety with an IP67 housing.
Applications and delivery
Applications
- Verification of earthing systems in electrical installations.
- Earth electrodes of buildings, substations and lightning protection.
- Quality checks of the earthing circuit from the measured result.
- Work by installation contractors and maintenance technicians.
Everything included
The set includes 30 m and 15 m leads on reels, a 2.2 m lead, a crocodile clip, two 25 cm ground probes, AA batteries, carrying case, straps and a calibration certificate; 80 cm probes and leads up to 200 m on spools are optional. At about 660 g with batteries and only 221 × 102 × 62 mm, the AMRU-10 travels to wherever the earthing is.
AMRU-10 — TECHNICAL SPECIFICATIONS
| Measuring methods | Technical 3-pole per EN 61557-5; 2-pole |
|---|---|
| Earth resistance range | 0.53…9999 Ω (UN = 50 V); display from 0.01 Ω |
| Accuracy | ±(3 % m.v. + 3 digits) to 199.9 Ω; ±5 % to 1999 Ω; ±8 % to 9999 Ω |
| Auxiliary electrodes | RH and RS: 0…19.9 kΩ; ±(5 % m.v. + 8 digits) |
| Interference voltage | 0…100 V; ±(10 % m.v. + 1 digit) |
| Measuring current | > 20 mA (short circuit); 125 Hz or 150 Hz |
| Measuring voltage | Selectable: 25 V or 50 V |
| Permitted disturbance | RE measured with interference up to 24 V |
| Power supply | 4 × AA alkaline batteries or NiMH accumulators |
| Display | Backlit segment LCD |
| Safety | CAT III 300 V; double insulation per EN 61010-1 |
| Protection class | IP67, per EN 60529 |
| Operating conditions | -10…+50 °C; humidity 20-90 % |
| Dimensions and weight | 221 × 102 × 62 mm; approx. 660 g with batteries |
| Standards | EN 61557-5, EN 61010-1, EN 61326-1, EN 61326-2-2 |
AMRU-10 — MEASUREMENT DATA
Earth resistance RE — 3-pole method
Measuring range acc. to EN 61557-5: 0.53 Ω…9999 Ω for test voltage UN = 50 V.
| Range Resolution | Accuracy |
|---|---|
| 0.00…19.99 Ω 0.01 Ω | ±(3% m.v. + 3 digits) |
| 20.0…199.9 Ω 0.1 Ω | ±(3% m.v. + 3 digits) |
| 200…1999 Ω 1 Ω | ±5% |
| 2000…9999 Ω 1 Ω | ±8% |
| Earth resistance RE — 2-pole method | |
| Range Resolution | Accuracy |
| 0.01…19.99 Ω 0.01 Ω | ±(3% m.v. + 3 digits) |
| 20.0…199.9 Ω 0.1 Ω | ±(3% m.v. + 3 digits) |
| 200…1999 Ω 1 Ω | ±5% |
| 2000…9999 Ω 1 Ω | ±8% |
| Interference voltage mea | asurement UN | |
|---|---|---|
| Range | Resolution | Accuracy |
| 0…100 V Measurement for 45…65 Hz; at le | 1 V east 2 measurements per second. | ±(10% m.v. + 1 digit) |
| Measurement for 45…65 Hz; at le | east 2 measurements per second. | |
| Resistance of auxiliary el | lectrodes RH, RS | |
| Range | Resolution | Accuracy |
| 0…999 Ω | 1 Ω | ±(5% + 8 digits) |
| 1.00…9.99 kΩ | 0.01 kΩ | ±(5% + 8 digits) |
| 10.0…19.9 kΩ | 0.1 kΩ | ±(5% + 8 digits) |
Test current at short circuit > 20 mA; measuring frequency 125 Hz (50 Hz networks) or 150 Hz (60 Hz networks); test voltage selectable 25 V or 50 V; maximum interference voltage during the RE measurement: 24 V.
"m.v." – measured value.