Phenix Technologies MRM-10 User manual

1
MRM-10
User’s Manual
MRM-10
Digital micro-ohmmeter
Phenix Technologies, Inc
75 Speicher Drive
Accident, MD 21520
GF-2016
© Phenix Technologies, Inc.
Rev 11/14/2016 nab

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MRM-10

SECTION 1: DANGER / GENERAL SAFETY PRECAUTIONS
WARNING !!
Complete Grounding of this unit is necessary for the safe operation of this equipment.
Disconnect inputs before ungrounding this equipment.

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MRM-10
GENERAL SAFETY PRECAUTIONS


HIGH VOLTAGE
This equipment is capable of providing POTENTIALLY LETHAL VOLTAGES! Improper
operation or test practices may result in injury or death to the operator or surrounding
personnel.
The operation of High Voltage test equipment should only be performed by personnel
familiar with HIGH VOLTAGE testing and safety procedures. The operator of this
equipment must be aware of all hazards associated with High Voltage testing. The
operator is responsible for himself and others in close proximity of the testing area.
Some General Safety Practices for working with High Voltage Test Equipment have
been listed below for your reference.
Become familiar with your instrument before performing an actual test
Know your work area, check that all circuits are de-energized and locked out.
Never work alone; always work with another qualified worker.
Mark off entire work area with barriers and warning tape.
Make all personnel aware of your testing activities.
Be aware of dangerous conditions that may arise from energizing a test
specimen.
Never modify test equipment; modifications to equipment could introduce an
unknown hazard or hinder a designed-in safety feature.
DO NOT operate damaged equipment. Remove power and do not use the
equipment until safe operation can be verified by service-trained personnel.
Phenix Technologies, Inc. assumes no liability for unsafe or improper use of test equipment.

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MRM-10
Specific Safety Precautions
This equipment should be operated only by qualified and duly trained people, closely observing the
corresponding safety regulations and instructions contained in this User’s Manual.
Check that the item to be measured is voltage free.
Before starting with the measurements, be sure that the battery is well charged and that the line voltage is
between specified limits.
Do not connect or disconnect the test leads during the measurement.
There are no adjustable parts or parts that can be replaced by the user within the equipment.
WARNING:
Taking out the Control Panel in order to have an access to the internal parts may be dangerous as there are
high voltages inside, capable of causing fatal accidents.
Cleaning of this instrument should be carried out using a soft cleaning liquid, after verifying that it doesn't
attack the plastic parts used in the case and in the Control Panel of this equipment.
This equipment should be used only by a trained and
competent person, strictly applying suitable safety
rules.
Used symbols
Caution, refer to User Guide.
Equipment complies with current EU Directives.
The rubbish bin with a line through it means that in the European Union,
the product must undergo selective disposal for the recycling of electric
and electronic material, in compliance with Directive WEEE 2002/96/EC.

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MRM-10
TABLE OF CONTENTS
SAFETY PRECAUTIONS
1. DESCRIPTION ............................................................................. 6
1.1. OPERATING PRINCIPLE ...................................................... 6
2. CONTROL PANEL ....................................................................... ` 7
3. POWER SUPPLY......................................................................... 8
3.1. BATTERY CONDITION.......................................................... 8
3.2. BATTERY CHARGER............................................................ 8
4. MEASUREMENT.......................................................................... 9
5. MESSAGES.................................................................................. 10
6. SOME NOTES ABOUT ACCURACY........................................... 11
7. RS232 OUTPUT........................................................................... 12
8. CLEANING ................................................................................... 13
9. REPLACEMENT FUSE................................................................ 14
10. TECHNICAL SPECIFICATIONS ................................................ 15
11. CUSTOMER COMMENTS / SUGGESTIONS ........................... Error! Bookmark not defined.

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MRM-10
1. Description
The MRM-10 micro-ohmmeter is a portable, microprocessor controlled instrument, used to accurately measure
very low contact resistances of breakers and switches, bus bars, transformers and engine windings, etc, with
test currents from 1mA to 10A.
Kelvin architecture (four-terminal method).
Digital reading, alphanumeric display.
Up to 4½ digits readings.
Powered by rechargeable battery or mains supply.
1 µΩresolution.
200 Ωmaximum reading.
1.1. Operating Principle
This device uses the Kelvin Bridge architecture, with four terminals, avoiding testing leads resistance to cause
error during measurement. The operator may choose test current and the reading is obtained by comparison
through internal high-stability standards. The result appears in the alphanumeric display that is very easy to
read.

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MRM-10
2. Control Panel
1. Fuse 13. Test Current Control
2. Power Cord Connector 14. Battery Key (measures battery charge condition)
3. Ground 15. STOP Key
4. RS-232 Data Output 16. START Key
5. Current Terminal (C+) 17. Hold Key (retains last measurement in the display)
6. Potential Terminals (P+ P-)
7. Current Terminal (C-)
8. ON / OFF Switch
9. Displays both measured resistance value
& messages
10. ON Indicator LED
11. Battery Charge Iindicator
12. Range & Test Current Selector
1
2
3
4
5
6
7
8
9
10
11
12
14
15
13
16
17

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MRM-10
3. Power Supply
Mains supply or internal battery powered
Battery: rechargeable, 12 V - 7 Ah.
Mains: 100 - 240 V~
At the end of the useful life, the battery has to be recycled or
disposed of properly in order to take care of the environment.
3.1. Battery Condition
The charge condition of the battery can be verified before or during the resistance measurement. In order to
achieve that, the operator has to press the battery key while the equipment is turned on. The bar graph shows
remaining charge as a percentile value. If during measurement the charge reaches a critical level, the display
will show the BAT message notifying that the charge level is low. After a few minutes the measurement will be
automatically interrupted in order to preserve the battery from a deep discharge that is prejudicial for its
expected useful life.
3.2. Battery Charger
The built-in battery charger is always active when the equipment is connected to the mains supply, even if the
On/Off switch is turned off.
Charging procedure:
Check that the On/Off switch is in Off.
Connect the equipment to the mains supply.
The battery charge indicator will display a red light up to completing the charge. At that point, it will change
to a green light, and remain so until the equipment is disconnected from the mains supply.

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MRM-10
4. Measurement
Check that the item to be measured is voltage free.
1. Before turning the equipment on, connect the test leads to the item to be measured and to the front panel
terminals.
2. Using the test current selector, choose the range and the current to be used.
3. Choose the power supply to use. If you are going to use the battery, advance to the following point. If you
are going to use the mains supply, plug the power cord into the connector.
4. Switch the equipment On using the On/Off.
5. The PRESS START message will appear showing that measurement can be started. Press the Start key.
Depending on the position of the test current control the LOW CURRENT message will turn up.
6. Turning the test current control clockwise increases the current. Adjust this control until obtaining the
desired value or until the current indicator (bar graph) indicates 100%. The bar graph will show the test
current value as a percentage of the nominal value selected by using the test current selector.
7. The lowest current for measuring is 10% of the nominal value. It is important to consider that the
measurement errors increase while test current decreases. The equipment accuracy is specified for test
currents higher than 80%.
8. The display will show the resistance value measured and the corresponding unit (Ω [ohms], mΩ [milli-
ohms] or µΩ [micro-ohms]).
9. The value can be retained in the display by pressing the hold key. Pressing this key again releases the
value.
10. Press the Stop key in order to finish the measurement. Do not turn Off the equipment without pressing the
Stop key.
11. Finally, after finishing measurements, turn the equipment Off using the On/Off switch.
CAUTION: Do not connect or disconnect the test leads
during the measurement.

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MRM-10
5. Messages
The opening message displays Phenix MRM 10. When turning the equipment On using the On/Off switch,
this introductory message briefly appears. During that time, the equipment carries out some functional checks.
WAIT...
This message appears each time the equipment needs to adjust any parameter in order to optimize the
readings.
PRESS START
The equipment is ready to start a measurement, thus the operator has to press the Start key.
LOW CURRENT
It shows that the test current is not enough to carry out the reading. It appears at the beginning of each test
and it stays on as the operator rotates the test current control clockwise, as necessary for the test current to
be higher than 10 % of the nominal current in the scale. The inappropriate connection of the cables may cause
a difficult circulation of test current. If this message keeps on being displayed, please check that the current
cables are connected appropriately.
OVER RANGE
It indicates that the measured resistance is higher than the maximum value readable in the selected range.
H
Indicates that the value is the one retained in the memory when pressing the hold key.
BAT
It shows that the battery is discharged. Recharge the battery.

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MRM-10
6. Notes about accuracy
In order to obtain the specified accuracy, the operator has to adjust the test current to a value higher than the
80% of the nominal value. If it were necessary, it is possible to use a lower current, but by doing this the
accuracy will be affected.
MRM-10 has an auto-compensation system that automatically eliminates the error produced by internal offset.
Thus, it is not necessary to carry out measurements by reversing the polarity in order to compute the average
value. Nevertheless, if the operator suspects that there is a difference of temperature between the contact
points that would generate thermoelectric voltages, it is necessary to carry out two measurements by reversing
the current cables and thus the circulation sense of the current through the resistance under measurement.
The resistance value to be measured will be the average between the values in one sense and in the contrary
(direct and inverse current).

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MRM-10
7. RS-232 Output
The equipment has a RS-232 data output in the control panel that can be used to register measurements in a
serial printer or data collector. The outputs are the following ones:
Pin 2: Rx ; Pin 3: Tx ; Pin 5: Gnd;
Rate: 4800 bps
8 bits - no parity - 1 stop bit (8,n,1)
Note: In order to assure the compatibility with most printers available in the market, the resistance units are
shown with the following symbols:
uR = micro-ohm
mR = milli-ohm
R = ohm

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MRM-10
8. Cleaning
The panel, terminals and connectors of the equipment must stay dry and clean. Cleaning should be made
using a wet cloth in water and a soft detergent or isopropyl alcohol (be sure that the products to be used for
cleaning do not affect plastic goods).

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MRM-10
9. Replacement Fuse
To check the instrument fuse, remove it with a screw driver. If the fuse is ruptured, replace it by another with
the following specifications:
Fuse Schurter, model SPT 5x20 (Time-lag) 5A/250V. High breaking capacity.

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MRM-10
10. Technical Specifications
Test currents
:
1 mA - 10 mA - 100 mA - 1 A - 10 A.
Each current may be continuously adjustable from 0 to 00%.
Resistance ranges
:
0 - 2000 µΩ @ 10 A
0 - 20 mΩ@ 10 A
0 - 200 mΩ@ 1 A
0 - 2000 mΩ@ 100 mA
0 - 20 Ω@ 10 mA
0 - 200 Ω@ 1 mA
Resolution
:
1 µΩ @ 10 A
Output voltage
:
Up to 10 Vdc. @ 1 A (open circuit).
Measurement principle
:
Four-terminal, Kelvin-type.
Basic accuracy
:
± 0.2% of reading ± 2 digits
Advanced features
:
Digital direct reading of very low resistances in the alphanumerical
display, with up to 4½ digits. Very fast and accurate measurements.
Serial data output
:
RS-232 @ 4800 bps. Suitable for data collection in an external serial
printer, computer or data-logger.
Environmental
protection
:
IP54 with closed lid.
Safety class
:
Meets the requirements of IEC 61010-1
Power supply
:
Rechargeable battery 12 V - 7 Ah or 100-240 V~ mains supply.
Built-in battery charger
:
100-240 V~ mains supply.
Operating temperature
range
:
23°F to 122°F (-5°C to 50°C)
Storage temperature
range
:
-13°F to 149°F (-25°C to 65°C)
Humidity range
:
95% RH (non condensing)
Weight
:
Approx. 8.7 kg (19 lbs.)
Dimensions
:
378 x 308 x 175 mm (15 x 12 x 7 in.)
Accessories
:
2 Combined current and potential leads (1.8 m, 70 in.).
1 Ground cable.
1 Communication cable (RS-232).
1 Power cord.
1 User guide.
1 Carrying bag.
Subject to technical change without notice.

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MRM-10
SECTION 11: CUSTOMER COMMENTS / SUGGESTIONS
Phenix Technologies made significant efforts to ensure that the materials in this Operator’s Manual
are correct. If there are concerns or comments as you have used this information, Phenix
Technologies appreciates any feedback.
Unit Serial Number:
SECT
PAGE(S)
COMMENT
Please return to Phenix Technologies, Engineering Department, 75 Speicher Drive, Accident, MD
21520 USA.
Phone: [phone], Fax [phone], or [e-mail]