CA 6250 User Manual PDF
CA 6250 User Manual PDF
CA 6250 User Manual PDF
A 6250
Microhmmtre
Microhmmeter
Mikro-Ohmmeter
Microhmmetro
Micrmetro
FRANAIS
ENGLISH
DEUTSCH
I TA L I A N O
E S PA N O L
Notice de fonctionnement
User's manual
Bedienungsanleitung
Libretto dIstruzioni
Manual de Instrucciones
Meaning of the
symbol
WARNING ! Consult the user manual before using the instrument.
Failure to follow or carry out the instructions in this user manual that are preceded by this symbol
may result in personal injury or damage to the instrument and the installations.
Signification of the
symbol
The instrument is protected by double or reinforced insulation and does not have to be earthed.
symbol is displayed.
disappears.
Do not disconnect the measuring cords until the symbol
Comply with the charging characteristics of the battery and use a fuse of the appropriate type and
rating; failure to do so may damage the instrument and void the warranty.
Set the switch to OFF when the instrument is not in use.
Check that none of the terminals is connected and that the switch is set to OFF before opening the
instrument.
Repairs and metrological verifications must be performed by approved, qualified personnel.
24
CONTENTS
1. PRESENTATION ............................................................................................................................ 26
2. DESCRIPTION ............................................................................................................................... 27
2.1 Front panel ............................................................................................................................... 27
2.2 Keys
..................................................................................................................................... 27
2.3 Display unit ............................................................................................................................... 28
2.4 RS 232 interface : characteristics ........................................................................................... 29
3. USE / PROCEDURE ...................................................................................................................... 29
3.1 Making a measurement ........................................................................................................... 29
3.1.1 Connections ................................................................................................................ 29
3.1.2 Sequence of use ......................................................................................................... 29
3.2 Selection of the measurement mode :
key .......................................................... 30
3.2.1 Measurement in inductive resistance mode .............................................................. 30
3.2.2 Measurement in non-inductive resistance mode ....................................................... 31
3.2.3 Measurement in non-inductive resistance mode with automatic triggering .............. 32
3.3 Temperature compensation : R() key ................................................................................... 32
3.3.1 Principle ....................................................................................................................... 32
3.3.2 Procedure .................................................................................................................... 33
3.4 Activating the alarms (ALARM) ............................................................................................... 33
3.5 Storing and retrieving measurements (MEM/MR) .................................................................. 33
3.5.1 Storing results (MEM) ................................................................................................. 33
3.5.2 Retrieving stored results (MR) ................................................................................... 34
3.6 Instrument configuration : SET-UP ........................................................................................... 34
3.6.1 Programming menu ..................................................................................................... 35
3.6.2 Erasing the memory .................................................................................................... 38
3.7 Printing results (PRINT/PRINT MEM) ..................................................................................... 38
3.7.1 Immediate printing of a measurement (PRINT) ......................................................... 38
3.7.2 Printing stored results (PRINT/MEM) ......................................................................... 39
3.8 List of coded errors .................................................................................................................. 39
4. CHARACTERISTICS ..................................................................................................................... 40
4.1 Characteristics ......................................................................................................................... 40
4.2 Power supply ............................................................................................................................ 40
4.3 Environmental conditions ......................................................................................................... 41
4.4 Physical characteristics ........................................................................................................... 41
4.5 Compliance with international standards ................................................................................. 41
5. MAINTENANCE ............................................................................................................................. 42
5.1 Maintenance ............................................................................................................................. 42
5.1.1 Changing the battery pack .......................................................................................... 42
5.1.2 Replacing the fuses ..................................................................................................... 42
5.1.3 Cleaning ....................................................................................................................... 42
5.2 Maintenance ............................................................................................................................. 42
5.2.1 Adjustment ................................................................................................................... 43
5.2.2 Updating the internal software .................................................................................... 44
6. WARRANTY ................................................................................................................................... 45
7. TO ORDER ..................................................................................................................................... 45
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1. PRESENTATION
The C.A 6250 microhmmeter is a top-quality portable digital measuring instrument with backlit LCD
display. It is designed to measure very small resistances.
Housed in a rugged construction-site type case with cover, the C.A 6250 is a self-contained instrument
powered by a rechargeable battery with built-in charger.
It provides 7 measurement ranges, from 5m to 2,500, that can be accessed and selected directly
on the front-panel rotary switch.
It uses the 4-wire measurement method (see 3.1.1), with automatic compensation of spurious voltages.
It has many advantages :
automatic detection of the presence of an external AC or DC voltage on the terminals, before or
during the measurement, which disables or stops the measurements when measurement accuracy
is no longer guaranteed,
3 different measurement modes depending on the nature of the resistance to be measured,
protection of the operator when a resistance having a large inductive component (motor, transformer,
etc.) is measured. After the measurement, the instrument automatically discharges the inductance
if the measuring cords are left connected to the inductive resistance measured.
programming of alarm thresholds (alarms in the form of audible beeps),
possibility of measuring the measurement temperature using a Pt100 jack on the front panel,
function for automatic calculation of the resistance at a reference temperature using the possibility
of selecting the type of metal the resistance is made of and its temperature coefficient,
extended memory making it possible to store approximately 1,500 measurements,
indication of the level of memory use,
indication of battery charge condition,
automatic switching of the backlighting to standby to save battery power,
RS 232 interface to print the results on a serial printer or export them to a PC.
Its main applications are:
bonding measurements,
component measurements,
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2. DESCRIPTION
2.1
-
2.2
Off
: instrument power off / setting for charging
2500
: 2500,0 range measuring current 1mA
250
: 250,00 range measuring current 10mA
25
: 25,000 range measuring current 100mA
2500m
: 2500,0m range measuring current 1A
250m
: 250,00m range measuring current 10A
25m
: 25,000m range measuring current 10A
5m
: 5,0000m range measuring current 10A
SET-UP
: instrument configuration
1 yellow START/STOP key: start/stop measurement
8 elastomer keys each having a primary function and a secondary function.
1 backlit LCD screen
1 receptacle for connection to line power to charge the battery
1 jack for connection of a Pt100 temperature probe,
1 RS 232 serial INTERFACE plug (9 pin contacts) for connection to a PC or to a printer.
KEYS
METAL
R()
ALARM
MEM
MR
Activate the secondary function written in yellow italics below each key. The
symbol appears on the screen.
Primary function: before starting the measurement, select the desired measurement
mode: inductive, non-inductive or non-inductive with automatic triggering.
Secondary function: select the metal for the temperature compensation calculation:
Cu, Al, or Other metal.
Primary function: activate/deactivate the temperature compensation function:
calculation of the resistance at a temperature other than the measurement
temperature.
Secondary function: activate/deactivate alarms. The direction and the triggering
value (high or low) are adjusted in the SET-UP menu
Primary function: store the measurement at an address identified by an object
number (OBJ) and a test number (TEST).
Secondary function: retrieve stored data (this function is independent of the setting
of the switch) except in the OFF and SET-UP settings.
&
Primary function: select the parameter to be modified (in wraparound mode, from
left to right). In SET-UP mode, access the adjustments of a function.
Secondary function: in SET-UP mode, shift the decimal point and select the unit.
4
PRINT
PRINT MEM
27
2.3
DISPLAY UNIT
Dual liquid crystal display
Secondary display unit : measurement parameters / memory address
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
2.4
The RS 232 jack can be used with 4 different peripherals (choice of 4 different links in SET-UP):
- PC:
activate RS232 link between the instrument and a computer
- PRNT:
activate RS232 link between the instrument and a printer
- TRIG:
activate the remote measurement triggering function
- VT100:
activate RS232 link between the instrument and a display console
Note that the RS232 can be switched OFF to deactivate the input and output functions of the connector
(saves battery power).
Selecting an RS232 link opens a submenu in which to choose the data rate between the instrument and
the peripheral. This adjustment is made in SET-UP (see 3.6)
The baud rate can be set to 4,800, 9,600, 19,200, or 31,250.
Data format: 8 data bits, no parity, 1 stop bit, hardware control (CTS)
3. USE / PROCEDURE
3.1
MAKING A MEASUREMENT
3.1.1 Connections
Connections are made in accordance with the 4-wire measurement principle; the set-up used is shown
in the figure bellow :
Where:
Ri = Internal resistance of the instrument.
Rf = Resistance of the measuring wires.
Rc = Contact resistance.
Rx = Resistance to be measured.
5. Connect the measuring cords to the instrument, then to the resistance to be measured.
6. The instrument indicates ST BY (standby). Press START to start the measurement and, if applicable,
STOP to stop it (this depends on the measurement mode selected).
Remark: Changing ranges during a measurement stops the measurement cycle; the instrument
returns to standby (ST BY).
7. The instrument displays the measurement result.
8. Then press MEM to store the result and validate by pressing again.
For a detailed description of result storage, see 3.5.
3.2
KEY
C
0
MES
100ms
120ms
640ms
1200ms
30
C = check of connections
0 = measurement of residual voltage (stored).
1,2,3...n = successive measurements of the voltage on the terminals of the resistance (interval
between two measurements: 120ms).
The delay stated for the first measurement (1,200ms) is an indication only; it can vary according to
the load measured.
Remarks:
The source of current is protected against overheating. If a measurement at 10A lasts too long (>
several tens of seconds) and causes a temperature rise, the current is cut off and the instrument
displays Err 05. The instrument must be allowed to cool down before another measurement can
be made.
After a measurement cycle, the instrument automatically discharges the inductance completely.
During this discharging, the instrument displays the following icon:
Never touch or disconnect the leads before the icon disappears.
Description :
press the START key.
automatic check of connection of the current and voltage wires: if the connection is incorrect, an
error message is displayed (Err 11 if the current wires are incorrectly connected, Err 12 if the
voltage wires are incorrectly connected); the instrument switches to standby; the cycle is resumed
when the connection is correct.
current not established, measurement of residual voltage Uo on the terminals of the resistance. If
this voltage is too high, the instrument displays Err 13.
establishment of current I.
measurement of the voltage on the terminals of the resistance U1 then cutoff of the current.
display of the measurement R = (U1 - Uo) / I
automatic stop at the end of the measurement. The instrument, in standby, is ready for another
measurement.
Operating diagram (Example: two measurement cycles)
OPER
STBY
C
O
MES
100ms
100ms
240ms
240ms
360ms
360ms
C = check of connections
0 = measurement of the residual voltage.
M = measurement of the voltage on the terminals of the resistance.
31
Remarks :
Description:
press the START key to activate the cycle.
connect the wires to the resistance. The instrument remains on standby until the links are established.
measurement of residual voltage Uo on the terminals of the resistance.
establishment of measuring current I, measurement of the voltage U1 on the terminals of the
resistance, and display of the measurement R = (U1-U0)/I
to make another measurement, it is necessary to release at least one link, then reestablish it.
cycle ended by pressing the STOP key
3.3
) KEY
TEMPERATURE COMPENSATION : R (
3.3.1 Principle
The metals used for the windings of certain components (e.g. the copper in transformers and motors)
have large temperature coefficients (of the order of 0.4%/C for copper and aluminium).
This makes resistance measurements strongly dependent on the temperature of the component.
The temperature compensation function is used to adjust the resistance measured, which depends
on the ambient temperature (measured or programmed), to the value it would have at a programmed
reference temperature.
The temperature-compensated resistance is calculated as follows:
R(tref)= R(tamb) * (1 + (alpha * tref ) )
1 + (alpha * tamb)
where
R(tamb):
resistance measured at ambient temperature by the instrument
tamb:
temperature measured by a Pt100 or programmed by the user
Alpha:
temperature coefficient of the selected metal (Aluminium, Copper, or Other metal)
tref:
programmed reference temperature to which the measurement is referred
tamb, alpha and tref are parameters that can be programmed in SET-UP (see 3.6.).
32
metal
Aluminium
Copper
Carbon (0-1850C)
Iron
3.3.2
per C
0,0043
0,00393
-0,00025
0,0050
metal
Lead
Mercury
Platinum
Zinc
per C
0,0043
0,00090
0,0038
0,0037
Procedure
first check the programming of the tamb, alpha, and tref parameters (see 3.6.) and the
connections.
press the R(q) key
the R(q) symbol and the metal selected are displayed steadily on the display unit.
the small display unit indicates the temperature tref then the temperature tamb.
once the measurement has been made, the instrument displays:
- on the small display unit, depending on the programming:
the programmed ambient temperature
or the temperature measured by the temperature sensor
or - - - - if the temperature sensor is validated but not connected or incorrectly
connected, or if the temperature measured is out of bounds (-10C to +55C).
- on the large display unit:
the compensated resistance value
Remark: Err 10 is displayed if a temperature is out of bounds or if the leads of the sensor become
disconnected.
3.4
+ R()).
The values of the alarms and their direction of activation are programmed in advance by the user in
SET-UP (see 3.6)
3.5
Measurement results can be stored at memory addresses identified by an object number (OBJ) and
a test number (TEST).
An object is a box in which 99 tests can be stored. An object can thus represent a device on which a
number of measurements/tests are to be performed.
Procedure:
1. When the measurement is over (result held on the display unit), press the MEM key.
The MEM symbol flashes and the small display unit indicates the first free OBJ:TEST number (e.g.
02 : 01). The main display unit then indicates FrEE.
The OBJ no. is that of the last measurement stored, but the TEST no. is incremented by 1.
OBJ:TEST can be changed at any time using the4and 56 keys.
If the user selects a memory address that is already occupied, OCC appears on the main display
unit.
If a new OBJ is selected, TEST is set to 01.
33
2. Pressing the MEM key again saves the measurement results at the selected memory address
(whether occupied or not).
The MEM symbol stops flashing and remains displayed. Pressing a key other than MEM or turning
the switch before the second press on MEM causes an exit from the save mode without storage
of the results.
3. To exit from the memory mode and return to measurement mode, turn the rotary switch.
Procedure :
1.
2. To exit from the memory mode after the consultation, press MR again or turn the rotary switch.
The content of a memory location is as follows:
- the 0BJ:TEST no. of the measurement,
- the range and measuring current settings,
- the measured value with any compensation,
- the R() symbol and symbol of the metal if the measurement was compensated,
- the active alarms at the time of the measurement.
Other items of information are also accessible by pressing a key :
- R()
: displays the coeff. of correction of the metal selected for compensated measurements.
: displays the ambient temperature at the time of the measurement for compensated
measurements.
- R()(twice): displays the reference temperature of the measurement for compensated
measurements.
- ALARM
: displays the alarm threshold, for measurements with an alarm active.
3.6
This function is used to configure the instrument and change its configuration as needed.
After the rotary switch is turned to SET-UP:
- all segments of the display unit light for 1 second,
- SEt then appears on the small display unit to prompt for a key press,
- the 56 key is then used to navigate in the parameter programming menu,
- the parameter to be modified is selected by pressing the 4key.
34
Remarks:
35
Parameter to be
key
display
modified
5
(1er push)
5
(2nd push)
5
(3 push)
5
(4 push)
5
(5 push)
5
(6 push)
5
(7 push)
5
(8 push)
5
(9 push)
5
(10 push)
5
(11 push)
5
(12 push)
5
(13 push)
secondary
symbol
Prnt
rS
BUZZ
number
Edsn
number
EdPP
Lan9
printing language
L9F
Lan9
trEF
reference temp.
value
trEF
tAnb
ambient temp.
nPrb
tAnb
nEtA
metal selection
value
nEtA
Cu or AI or
Other metal
ALPH
Other metal
coeff.
coeff. value
ALPH
Other metal
dE9
temperature
unit
dE9c
dE9
ALAr
alarms (values
and directions)
value
ALAr
LI9H
duration of
backlighting
t=1
LI9ht
nEn
erasure of
memory
dEL
nEn
RS
communication
BUZZ
buzzer sound
level
EdSn
display of serial no.
EdPP
display of
program no.
main
ALARM +
Remark: The SEt function can also be adjusted. This possibility is however provided for maintenance
of the instrument only and is password-protected (see Maintenance).
36
value
changing of values
- successive presses on
Fr / 9b
- press on
Prb or nPrb
si nPrb : -10 ... 55C
Cu or AI or
Other metal
0 ... 100,00
(10-3/C)
- press on
ALARM 1 or 2 /5or6/
5m to 2500
- press on
dEL or dEL O
(all memory or object)
- press on
5then4
37
3.7
INSTRUMENT NUMBER:
LOW RESISTANCE MEASUREMENT
OBJECT:
TEST:
DESCRIPTION:
...
....
..
DATE:
.
MEASUREMENT:
-- / -- / ---METAL:
NON-INDUCTIVE
METAL COEFF.:
Cu
MEASUREMENT TEMPERATURE:
3.93
REFERENCE TEMPERATURE:
23.2 Cel
RESISTANCE MEASUREMENT:
20.0 Cel
MEASUREMENT REFERRED TO TREF:
1294.6Ohm
REMARK:.
1287.2Ohm
....
.
DATE OF NEXT TEST:
..
-- / -- / ----
38
3.8
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Err
Warning:
If error message 2, 3, 4, or 8 appears, the instrument must be switched off and sent to a
qualified organization for repair.
....
..
.
-- / -- / ---NON-INDUCTIVE
Cu
3.93
23.2 Cel
20.0 Cel
1294.6Ohm
1287.2Ohm
.
.
..
-- / -- / ----
39
4. CHARACTERISTICS
4.1
CHARACTERISTICS
Remark: accuracies are stated in the form (n% read + C) where read = reading and C = a Constant,
in practical units.
They apply to the instrument placed in the reference conditions (see 4.3), after 1 hour of warming up.
4-wire measurement with compensation of spurious voltages.
(measurements made under reference conditions as per publication CEI 485 (national standards NF
C 42-630 and DIN 43751)).
Range
Resolution
Accuracy over 1
year
Measuring
current
Voltage
drop
5.0000 m
25.000 m
250.00 m
2500.0 m
25.000
250.00
2 500.0
0.1
1
10
0.1 m
1 m
10 m
100 m
0.15% + 1,0
0.05% + 3
0.05% + 30
0.05% + 0,3 m
0.05% + 3 m
0.05% + 30 m
0.05% + 300 m
10 A
10 A
10 A
1A
100 mA
10 mA
1 mA
50 mV
250 mV
2500 mV
2500 mV
2500 mV
2500 mV
2500 mV
Temperature coefficient from 0C to 18C and from 28C to 50C : 1/10 of the accuracy per / C.
4.2
POWER SUPPLY
in standby :
, this means that the charge of the battery is low.
It must then be charged
The instrument can be charged only when OFF, and a full charge takes approximately 5h.
40
4.3
Voltage
drop
50 mV
250 mV
2500 mV
2500 mV
2500 mV
2500 mV
2500 mV
flashes
ENVIRONMENTAL CONDITIONS
Reference domain :
23C 5C
45% to 75% RH
Extreme domain :
-10C to +55C
10% to 80% RH without condensation.
4.4
PHYSICAL CHARACTERISTICS
4.5
41
5. MAINTENANCE
5.1. MAINTENANCE
5.1.1. Changing the battery pack
st
(1 press)
nd
Important remarks:
Changing the battery causes stored data to be lost.
Avoid storing the instrument with the battery charge too low.
If the instrument is left unused for a long time (more than 2 months), the charging time will be longer.
Before using the instrument again, it is therefore best to carry out 3 complete charging/discharging
cycles.
5.1.3 Cleaning
The instrument must be disconnected from any source of electricity.
Use a soft cloth slightly moistened with soapy water. Rinse with a damp cloth and dry rapidly with a dry
cloth or forced air. Do not use alcohol, solvents, or hydrocarbons.
5.2
MAINTENANCE
The primary function of the programming menu is reserved for maintenance use and is protected by a
5-digit password :
- set the rotary switch to SET-UP; SET is then displayed
- enter the programming mode by pressing the4key
- enter the pasword; the factory value is 09456.
42
(2 press)
rd
(3 press)
th
(4 press)
th
(5 press)
CP
Ad
nC
UP
Fr
When the password has been validated, a submenu proposes the various maintenance functions :
- the 56 key is then used to navigate in the functions menu,
- the desired function / command is selected by pressing the4key
st
(1 press)
nd
(2 press)
rd
(3 press)
th
(4 press)
th
(5 press)
CPt A
AdJ
nCOEF
UP9
FrEq
5.2.1 Adjustment
As part of the tracking of metrological quality, the user may be led to perform periodic performance
checks him/herself. The checks must include the usual metrological precautions. Comply with the
following instructions.
The operations are performed in the reference conditions, i.e.:
Temperature of the room: 23C 5C.
Relative humidity: 45% to 75%.
The standards that make up the checking chain must be such that the errors at the testing points are
known and are 0.01% for the resistance standards, with allowance for the factors of influence
encountered.
If this check shows that one or more characteristics of the instrument are outside the specified
tolerances, you must:
Adjustment procedure
RECOMMENDATIONS
The instrument was adjusted in the factory. Any untimely work irreversibly alters the adjustments
of the instrument.
The person responsible for the use of this instrument must make sure that the person in charge
of the work has been informed of the precautions to be taken in performing this operation.
For the adjustment to be performed under ideal conditions, Chauvin Arnoux recommends
returning the instrument to its workshops.
Failure to comply with these recommendations may void the warranty.
43
This operation must be performed under the following stable climatic conditions:
Temperature: 23C 5C.
Humidity: 45% to 75%.
Warm-up time: 1 hour.
The temperature of the instrument must be stabilized, as well as the temperatures of the standards. If
these conditions cannot be met, returning the instrument to the factory is preferable.
To adjust the instrument, it is necessary to have resistances calibrated with an uncertainty less than or
equal to 1x10-4. The standards must be able to withstand the currents of the corresponding ranges.
The following ranges must be adjusted: Pt100, 5m, 25m, 250m, 2,500m, 25, 250, 2,500.
The measurement ranges are adjusted at one point.
We recommend standards having values greater than 80% of full scale of the ranges.
The Pt100 range is not a measurement range; it is used for temperature compensation measurements;
it must therefore also be adjusted, at two points, a low point and a high point.
We recommend using standards close to 100 for the low point and 115 for the high point, the lower
and upper limits being 98 and 120.
For the adjustments of the ranges, connect the standards using the measurement connectors.
For the adjustment of the Pt100 range, connect the standards to the connector of the probe.
Reminder: The maintenance menu is password-protected.
Adjusting the 5m, 25m, 250m, 2500m, 25, 250 and 2,500m ranges:
- in the SEt maintenance menu, select the AdJ command,
- select the range to be adjusted and check that the standard is in fact connected,
- select AdJH and enter the value of the standard,
- select MEASH: the adjustment is then performed,
- the -AdJ- message indicates that the adjustment is over and was successful.
44
Important:
- the transmission rate for this update is 19,200 bauds.
- if the update is interrupted before it is complete, it is impossible to restart the instrument. Downloading
must be resumed after setting the instrument back to awaiting transfer.
6. WARRANTY
Unless otherwise stated, our warranty is valid for the twelve months following the date on which the
equipment is made available (extract from our General Conditions of Sale, available on request).
7. TO ORDER
C.A 6250 .............................................................................................................................. P01.1432.01
Spare parts :
jset of 10A Kelvin clamps (with 2-m cables) .................................................................. P01.1017.94
Euro power supply cord ................................................................................................. P01.2951.74
GB power supply cord .................................................................................................... P01.2952.53
6V / 8,5Ah NiMH battery pack ........................................................................................ P01.2960.30
10 6,3 x 32 fuses, 16A/250V .......................................................................................... P01.2970.89
10 5,0 x 20 fuses, 2A/250V ............................................................................................ P01.2970.90
carrying bag .................................................................................................................... P01.2980.66
45