Micro Ohmmeters
RMO-G Series
Micro Ohmímetros
Lightweight – from 8 to 11,5 kg /17.6 lbs to 25.4 lbs Powerful – from 0 to 800 A DC
Measuring range 0 – 999,9 mΩ (up to 6 Ω) Best resolution 0,1 μΩ (0,01 μΩ with “HP” module)
Typical accuracy ± (0,1 % rdg + 0,1 % FS) Remote Control Unit (optional) Both Sides Grounded Unit (optional)
A built-in High Precision module (optional)
- SINGLE / CONTIN / BSG / DTRtest modes
Description
RMO-G series of Micro Ohmmeters (hereafter referred to as “RMO-G”) contain 7 models: RMO100G, RMO200G, RMO300G, RMO400G, RMO500G, RMO600 and RMO800G.
All RMO-G models are based on a state of the art technology, using the most advanced switch mode technique available today. The main difference between these models is the maximum test current that can be generated (100 A for RMO100G, 200 A for RMO200G, …, 600 A for RMO600G, up to 800 A for RMO800G model).
RMO-G generates a true DC ripple-free current with automatically regulated test ramps. During a test the RMO-G ramps with increasing current before measuring and decreasing current after the measurement. This eliminates magnetic transients.
Communication between the RMO-G and a PC is through an USB (as standard) or an RS232 cable (as an option). Using the DV-Win the result can be arranged as an Excel spread-sheet which can be later shown as a diagram and printed for a report.
The set is equipped with a thermal and an overcurrent protection. The RMO-G has a very high ability to cancel electrostatic and electro-magnetic interference in HV electric fields. It is achieved by very efÏcient filtration. The filtration is made utilizing a proprietary hardware and software.
The RMO-G instrument has four separate test modes:
- SINGLE mode
- CONTIN mode
The RMO-G instrument can store internally up to 500 measurements. All measurements are time and date stamped. Using the DV-Win soft-ware a test can be performed from a PC and the results can be obtained directly on the PC.
- BSG mode (Both Sides Grounded)
- DTRtest mode (Dead Tank Resistance)
Single Test
The RMO-G instrument generates a filtered (true ripplefree) DC current and output it in an automatically regulated current ramp. By sloping the current up and down, magnetic transients are virtually eliminated.
Below is an example of single test ramp for the 100 A current.
BSG test
Grounding circuit breakers from both sides provides increased safety for testing personnel comparing with only one side grounding method.
This test mode is specially designed for Both Sides Grounded testing. A special current clamp meter supplied from the instrument is used for measuring the current through the groundings. The test setup is very simple (same as for the SINGLE test) and all calculations are made automatically by the device internal algorithm.
DTRtest
Presence of current transformers (CT) on the dead tank circuit breakers may introduce errors during contact resistance measurement due to CT magnetizing process. For this reason, it is necessary to saturate a CT prior to measurement.
Continuous Test
RMO-G can generate DC current continuously in predefined test durations, as presented in the table below.
Continuous Test
| Test current (A) | Maximum duration | Rest time (min) |
|---|---|---|
| Up to 100 A | Continuous | 0 |
| 200 A | 150 s | 2,5 min |
| 300 A | 90 or 150 s | 3 or 15 min |
| 400 A | 50 s | 2,5 min |
| 500 A | 30 s | 2 min |
| 600 A | 20 s | 2 min |
| 800 A | *5 s | 1 min |
*in standard version CONTIN mode is available up to 600 A, but it can be available for 800 A (5 s) as per request
To prevent overheating, certain duty cycles apply depending on the test current being used.
DTRtest menu is specially designed for resistance measurement of the dead tank circuit breakers. All calculations for detecting the saturated condition of CTs are done by internal algorithm. Accordingly, the process of measurement parameters setting and testing in this mode is very simple and does not differ much from live tank circuit breaker testing (in SINGLE / CONTIN test modes).
High – Precision module (optional)
The high-precision module is newly developed optional built-in addition to our RMO-G micro ohmmeters. It provides an increased precision and offers a highly accurate contact resistance measurement: ± (0,1 % rdg + 0,1 % FS) accuracy at range from 0,01 μΩ to 99,99 μΩ, with 0,01 μΩ resolution.
RMO-G devices with the built-in High Precision Module may be used for applications on very small resistance measurements of non-inductive test objects. This requirement is usually met at resistance inspections of generator circuit breakers, welding joints, GIS testing, etc.
Aplication
Typical application is measuring resistance of noninductive test objects:
- High, middle and low voltage circuit breakers (live and dead tank)
- High, middle and low voltage disconnecting switches
- Gas Isolated Switchgears (GIS)
- High-current bus bar joints
- Cable splices
- Welding joints
- Fuses
Connecting the Test Object to RMO-G
The connection diagram of the RMO-G devices corresponds to the Kelvin’s (four point) measurement principle. The measuring cables from the “Voltage Sense” sockets are attached as close as possible to Rx, and in between the current feeding cables. That way, a resistance of both cables and clamps is almost completely excluded from the resistance measurement.
Remote Control Unit
The RMO Remote Control Unit is an optional control unit that is used to start and stop the tests from a remote location, away from the actual RMO-G.
Provided that, for a series of tests, the same test current is fed through the test object, multiple measurements can be carried out with the RMO Remote Control Unit.
Connecting RMO-G to a Both Sides Grounded Circuit Breaker
Using RMO-G with both sides grounded option it is possible to make safer measurement of breakers with both terminals of the breaker grounded.
Current through circuit breaker
Current through groundings
Using the RMO-G with a current clamp-meter is an additional safety feature. Measurement of a circuit breaker contact resistance is done with both sides of the breaker grounded.
The RMO-G device will measure the current through the ground circuit connection and add this value to the selected test current value in order to provide the selected test current through the test object.
Beneficios y características
The main benefits and features of RMO-G devices are listed below:
- Very high output power (output voltage multiplied with output current) enables two main advantages:
- 1. Wide resistance measurement range even when very high currents are used.
e.g. RMO600G can test up to 5,3 mΩ with 600 A test current when 5 m / 50 mm2 current cables are used..
- The best resolution of RMO-G is 0,1 μΩ at 999,9 μΩ range as standard. Optionally, the 0,01 μΩ resolution can be provided at 99,99 μΩ range (upon request or in case of built-in High Precision module).
Several advanced features are available as standard/ optional accessories:
- Rmax feature – pass/fail criteria
- Built-in thermal printer (optional)
- 2. Use of thinner/longer test cables, depending of the customer requirement.
e.g. RMO100G can use 20 m current cables with cross-section of only 16 mm2 for testing circuit breakers with 100 A test current.
- The output current is filtered and has a ripple of less than 1 %.
- The instrument has a very high typical accuracy ± (0,1 % rdg + 0,1 % FS).
- USB or RS232 communication port
- Bluetooth communication (optional)
- DTRtest mode – a special mode for Dead Tank circuit breakers testing
- A built-in High Precision module (available as option) – provides an increased precision and offers a highly accurate contact resistance measurement in the range from 1 μΩ to 30 μΩ, with 0,01 μΩ resolution.
DV-Win software
DV-Win software provides acquisition and analysis of the test results, as well as control of all the RMO-G functions from a PC. The DV-Win also provides several advanced features as a supplement to multiple functions of RMO-G devices. Testing in Continuous mode is upgraded with a sample time feature which allows user to record test results in specific time intervals set in seconds.
After performed measurements results can be saved in a various formats and test report can be generated and saved or printed. Result can also be downloaded from the device to the PC by use of several different search filters.
For the RMO-G form of DV-Win software there is Help menu available, with detailed instructions and explanations of all functions and features.
DV-Win Main Features
- Full control of the device in test
- Test reports *available in several formats
- Several filters for results download to PC
- Test plans
- Sampling time feature for CONTIN mode
Technical data
Mains power supply
- Connection according to IEC/EN60320-1; C320
- Mains supply: 90 V – 264 V AC
- Frequency: 50 / 60 Hz
Medición
- Resistance range: 0 – 999,9 mΩ* for RMO100 – 600G, *expandable up to 6 Ω
- 0 – 499,9 mΩ for RMO800G
- Resolution
- Power consumption
| Model | @ 230 V CA | @ 115 V CA |
|---|---|---|
| RMO100G | 1190 VA | 1130 VA |
| RMO200G | 1815 VA | 1810 VA |
| RMO300G | 2400 VA | 2115 VA |
| RMO400G | 3570 VA | 2710 VA |
| RMO500G | 3970 VA | 3920 VA |
| RMO600G | 4720 VA | 4145 VA |
| RMO800G | 5010 VA | 3510 VA |
| (0,1 μΩ - 99,99 μΩ | 0,01 μΩ)* |
|---|---|
| *optional resolution at this range | |
| 0,1 μΩ – 999,9 μΩ | 0,1 μΩ |
| 1,000 mΩ - 9,999 mΩ | 1 μΩ |
| 10,00 mΩ - 99,99 mΩ | 10 μΩ |
| 100,0 mΩ - 999,9 mΩ | 0,1 mΩ |
| *1,000 Ω – 6,000 Ω | 1 mΩ |
- Typical accuracy ± (0,1 % rdg + 0,1 % FS)
Display
| • Fuse: | Type F |
|---|---|
| RMO100A & RMO200A | 12 A / 250 V |
| RMO300A & RMO400A | 15 A / 250 V |
| RMO500A & RMO600A | 20 A / 250 V |
| RMO800G | 20 A / 250 V |
- LCD screen 20 characters by 4 lines
- LCD display with backlight, visible in bright sunlight.
Interface
- RMO-G is equipped with an USB port
- optional: RS232 (connection to an external computer)
Output data
- optional: Bluetooth communication interface
- Test current ranges and load intervals:
| Model | Test current** | Test duration |
|---|---|---|
| RMO100G | 100 A | Unlimited |
| RMO200G | 200 A | 150 s |
| RMO300G | 300 A | 150 s |
| RMO400G | 400 A | 60 s @300 A |
| RMO500G | 500 A | 30 s |
| RMO600G | 600 A | 20 s |
| RMO800G | 800 A | *5 s |
*in standard version CONTIN mode is available up to 600 A, but it can be available for 800 A (5 s) as per request
**Courant d’essai sélectionnable par pas de 1 A (sur demande)
- Full Load Voltages at maximum current
| Modelo | @ 230 V CA | @ 115 V CA |
|---|---|---|
| RMO100G | 7,15 V | 6,80 V |
| RMO200G | 6,80 V | 5,90 V |
| RMO300G | 6,00 V | 4,80 V |
| RMO400G | 6,70 V | 4,40 V |
| RMO500G | 5,95 V | 5,10 V |
| RMO600G | 5,90 V | 3,80 V |
| RMO800G | 4,70 V | 2,85 V |
Test Result Storage
- RMO-G can store up to 500 measurements
Printer (optional)
- Thermal printer
- Paper width 80 mm / 3.2 in
Dimensions and weight
| Model | Dimensions (WxHxD) mm / in | Weight |
|---|---|---|
| RMO100G | 8 kg / 17.6 lbs | |
| RMO200G | 405 x 165 x 330 mm | 8 kg / 17.6 lbs |
| RMO300G | 7.8 x 10 x 15 in | 8 kg / |
| RMO300G RMO400G | *RMO 100G/200G/300G/400G /500G in version without built-in thermal printer | 17.6 lbs 9 kg / 20 lbs |
| RMO500G | 9 kg / 20 lbs | |
| RMO600G | 480 x 190 x 385 mm | 11 kg / |
| RMO600G | 18.9 x 7.48 x 15.16 in | 24.3 lbs |
| RMO8006 | *RMO600G/RMO800G and all RMO-Gs in version with built-in thermal printer | 11,5 kg / 25,4 lbs |
Environmental protection
- Ingress protection rating: IP67 *with closed lid
Environmental conditions
- Operating temperature:
- 20 ºC - +55 ºC / -4 ºF - +131 ºF
- Storage & transportation:
- 40 ºC - +70 ºC / -40 ºF - +158 ºF
- Relative humidity 5% - 95%, non-condensing
- Altitude: up to 2000 m
Applicable Standards
- Installation/overvoltage: category II
- Pollution: degree 2
- Low Voltage Directive: 2014/35/EU (CE conform), EN 61010-1
- EMC Directive 2014/30/EU (CE conform) (former 2004/108/EC) Applicable standard: IEC/EN 61326-1
- CAN/CSA-C22.2 No.61010-1, 2nd edition, including Amendment 1
Warranty
- 3 years
All specifications herein are valid at ambient temperature of + 25 °C and recommended accessories.
Specifications are subject to change without notice.
Accesories
- * Besides battery clamps, current cables are also available with C clamps or with alligator clamps (as option)
** Besides isolated alligator (A2) clamps, sense cables are also available with semi-isolated alligator (A1) clamps or with TTA clamps (as option)
Recommended cross-sections for RMO-G models:
| CROSS SECTION/ LENGHT | 16 mm2 | 25 mm2 | 35 mm2 | *50 mm2 | *70 mm2 | *95 mm2 |
|---|---|---|---|---|---|---|
| 5 m | RMO100A | RMO200A | RMO300A & RMO400A | RMO500A & RMO600A | - | *RMO800G |
| 10 m | RMO100A | RMO200A | RMO300A & RMO400A | RMO500A & RMO600A | - | *RMO800G |
| 15 m | - | RMO100A | RMO200A | RMO300A & RMO400A | RMO500A & RMO600A | - |
*RMO800G device can use cables with 50, 70 or 95 mm2 cross-section, depending of the re- quired resistance measurement range at 800 A test current..
Order info
| Instrument with included accessories | Article No. |
|---|---|
| RMO100G-N-00 | |
| RMO200G-N-00 | |
| Micro Ohmmeter RMO-G | RMO300G-N-00 |
| - DV-Win PC software including USB cable - Mains power cable | RMO400G-N-00 |
| - Mains power cable - Ground (PE) cable | RMO500G-N-00 |
| RMO600G-N-00 | |
| RMO800G-N-00 | |
| Recommended accessories | Article No. |
| Current cables 2 x 5 m, *XX mm2 with battery clips | C2-05-XXYMBY** |
| Sense cables 2 x 5 m with alligator clips | S2-05-02BPA2 |
| Transport case *RMO100G/200G/300G/400G/500G in version without built-in thermal printer | HARD-CASE-SC |
| Cable bag | CABLE-BAG-00 |
| Optional accessories | Article No. |
| Transport case *RMO100G/200G/300G/400G/500G in version without built-in thermal printer | HARD-CASE-SC |
| Transport case *RMO600G/RMO800G and all RMO-Gs in version with built-in thermal printer | HARD-CASE-LC |
| Cable plastic case – medium size | SCABLE-CAS-02 |
| Test shunt 100 μΩ (600 A/60 mV) | SHUNT-600-MK |
| Current cables 2 x 10 m, *XX mm² with battery clips | C2-10-XXYMBY** |
| Current cables 2 x 15 m, *XX mm² with battery clips | C2-15-XXYMBY** |
| Current extension cable 2 x 10 m, *XX mm² | E2-10-XXYMYF |
| Sense cables, extension 2 x 10 m | E2-10-02BPBP |
| Sense cables 2 x 10 m with alligator clips | S2-10-02BPA2 |
| Sense cables 2 x 15 m with alligator clips | S2-15-02BPA2 |
| Built-in thermal printer | PRINT-080-00 |
| High Precision Module (built-in) | RMO-HPMM-DG0 |
| Remote control unit | RMORCU-09-00 |
| Remote control test probes (one with trig button) | RMO-RCTP-TB0 |
| Current clamp 30/300 A power supplied from the instrument with extension 5 m (Both Sides Grounded Unit) | CACL-0300-06 |
*XX – Cross-section of current cables varies, depending of the ouput power of the model. **YMBY – For RMO100G and RMO200G without built-in thermal printer: YMBY=LMB1; For RMO100G and RMO200G with built-in thermal printer and for other models: YMBY=VMB3 e.g.:
For RMO200G without built-in thermal printer, the article number for current cables 10 m/25 mm2 cross-section is C2-10-25LMB1 For RMO600G, the article number for current cables 5m/50 mm2 is C2-05-50VMB3.