E1620
DIGITAL MILLI-OHMMETER
INSTRUCTION MANUAL
E1620
DIGITAL MILLI-OHMMETER
INSTRUCTION MANUAL
Martindale Electric Co Ltd
Martindale Electric Co Ltd
Metrohm House
Penfold Trading Estate
Imperial Way
Watford
Herts
WD24 4YY
Tel: + 44 (0) 1923 441717
Fax: + 44 (0) 1923 446900
E-mail: sales@martindale-electric.co.uk
Web: www.martindale-electric.co.uk
CMR0073
Issue 4 07/04 Martindale Electric Co Ltd
Martindale Electric Co Ltd
Metrohm House
Penfold Trading Estate
Imperial Way
Watford
Herts
WD24 4YY
Tel: + 44 (0) 1923 441717
Fax: + 44 (0) 1923 446900
E-mail: sales@martindale-electric.co.uk
Web: www.martindale-electric.co.uk
CMR0073
Issue 4 07/04
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TABLE OF CONTENTS
TABLE OF CONTENTS
1. SAFETY RULES
2. GENERAL DESCRIPTION
3. FRONT PANEL LAYOUT
4. PREPARATION FOR USE
5. OPERATING INSTRUCTIONS
5.1 Preliminary Checks
5.2 Precautions
5.3 Taking Measurements
5.4 Applications
5.5 Customer Test Leads
5.6 Thermal Effects
5.7 Battery Replacement
5.8 Fuse Replacement
5.9 Input Limits
6. SPECIFICATIONS
6.1 Electrical
6.2 Mechanical
6.3 Environmental
7. SPARES & ACCESSORIES
8. LIMITED WARRANTY
PAGE
1-3
4-5
5
6
7-9
9-10
10-11
11-12
12-13
13-14
14
14-15
15
15-16
16-17
17
18
19
TABLE OF CONTENTS
TABLE OF CONTENTS
1. SAFETY RULES
2. GENERAL DESCRIPTION
3. FRONT PANEL LAYOUT
4. PREPARATION FOR USE
5. OPERATING INSTRUCTIONS
5.1 Preliminary Checks
5.2 Precautions
5.3 Taking Measurements
5.4 Applications
5.5 Customer Test Leads
5.6 Thermal Effects
5.7 Battery Replacement
5.8 Fuse Replacement
5.9 Input Limits
6. SPECIFICATIONS
6.1 Electrical
6.2 Mechanical
6.3 Environmental
7. SPARES & ACCESSORIES
8. LIMITED WARRANTY
PAGE
1-3
4-5
5
6
7-9
9-10
10-11
11-12
12-13
13-14
14
14-15
15
15-16
16-17
17
18
19
1. SAFETY RULES
The E1620 has been designed with safety in mind. However, no
design can completely protect against incorrect use. Electrical
circuits can be dangerous and even lethal through lack of caution
or poor safety practises. The following rules will minimise the
danger:
(1) Read the Instruction Manual carefully and completely
before using this instrument. Fully understand the
instructions before using this tester. Follow the
instructions in the Manual for every test. Take all the
precautions recommended. Never exceed the limits of
this tester.
(2) The circuit to be tested must be de–energised and
isolated before connections are made to it.
(3) Do not use test leads, probes or crocodile clips that are
dirty, damaged or have broken or cracked insulation.
Such accessories should immediately be removed and
repaired.
(4) Always disconnect the test leads before replacing the
internal fuse or the batteries. Always replace the fuse
or batteries with the type specified and ensure that they
are correctly fitted.
(5) Double check the switch setting and lead connections
before taking measurements.
14. LIMITED WARRANTY
Martindale Electric Limited warrant instruments and test equipment
manufactured by them to be free from defective material or factory workmanship
and agree to repair or replace such products which, under normal use and service,
disclose the defect to be the fault of our manufacturing, with no charge for parts and
service. If we are unable to repair or replace the product, we will make a refund of
the purchase price. Consult the Instruction Manual for instructions regarding the
proper use and servicing of instruments and test equipment. Our obligation under
this warranty is limited to repairing, replacing or making refund of any instrument
or test equipment which proves to be defective within 24 months from the date
of original purchase.
This warranty does not apply to any of our products which have been repaired or
altered by unauthorised persons in any way so as, in our sole judgement, to injure
their stability or reliability, or which have been subject to misuse, abuse,
misapplication, negligence or accident or which have had the serial numbers altered,
defaced or removed. Accessories, not of our manufacture used with this product,
are not covered by this warranty.
To register a claim under the provisions of this warranty, return the instrument or
test equipment to Martindale Electric Limited, Metrohm House, Penfold Trading
Estate, Imperial Way, Watford WD24 4YY, UK. Upon our receipt and inspection
of the product we will advise you as to the disposition of your claim.
ALL WARRANTIES IMPLIED BY LAW ARE HEREBY LIMITED TO A PERIOD
OF 24 MONTHS, AND THE PROVISIONS OF THE WARRANTY ARE
EXPRESSLY IN LIEU OF ANY OTHER WARRANTIES EXPRESSED OR
IMPLIED.
The purchaser agrees to assume all liability for any damages and bodily injury which
may result from the use or misuse of the product by the purchaser, his employees, or
others, and the remedies provided for in this warranty are expressly in lieu of any
other liability Martindale Electric Limited may have including incidental or
consequential damages.
Martindale Electric Limited reserve the right to discontinue models at any time,
or change specification, price or design, without notice and without incurring any
obligation.
14. LIMITED WARRANTY
Martindale Electric Limited warrant instruments and test equipment
manufactured by them to be free from defective material or factory workmanship
and agree to repair or replace such products which, under normal use and service,
disclose the defect to be the fault of our manufacturing, with no charge for parts and
service. If we are unable to repair or replace the product, we will make a refund of
the purchase price. Consult the Instruction Manual for instructions regarding the
proper use and servicing of instruments and test equipment. Our obligation under
this warranty is limited to repairing, replacing or making refund of any instrument
or test equipment which proves to be defective within 24 months from the date
of original purchase.
This warranty does not apply to any of our products which have been repaired or
altered by unauthorised persons in any way so as, in our sole judgement, to injure
their stability or reliability, or which have been subject to misuse, abuse,
misapplication, negligence or accident or which have had the serial numbers altered,
defaced or removed. Accessories, not of our manufacture used with this product,
are not covered by this warranty.
To register a claim under the provisions of this warranty, return the instrument or
test equipment to Martindale Electric Limited, Metrohm House, Penfold Trading
Estate, Imperial Way, Watford WD24 4YY, UK. Upon our receipt and inspection
of the product we will advise you as to the disposition of your claim.
ALL WARRANTIES IMPLIED BY LAW ARE HEREBY LIMITED TO A PERIOD
OF 24 MONTHS, AND THE PROVISIONS OF THE WARRANTY ARE
EXPRESSLY IN LIEU OF ANY OTHER WARRANTIES EXPRESSED OR
IMPLIED.
The purchaser agrees to assume all liability for any damages and bodily injury which
may result from the use or misuse of the product by the purchaser, his employees, or
others, and the remedies provided for in this warranty are expressly in lieu of any
other liability Martindale Electric Limited may have including incidental or
consequential damages.
Martindale Electric Limited reserve the right to discontinue models at any time,
or change specification, price or design, without notice and without incurring any
obligation.
1. SAFETY RULES
The E1620 has been designed with safety in mind. However, no
design can completely protect against incorrect use. Electrical
circuits can be dangerous and even lethal through lack of caution
or poor safety practises. The following rules will minimise the
danger:
(1) Read the Instruction Manual carefully and completely
before using this instrument. Fully understand the
instructions before using this tester. Follow the
instructions in the Manual for every test. Take all the
precautions recommended. Never exceed the limits of
this tester.
(2) The circuit to be tested must be de–energised and
isolated before connections are made to it.
(3) Do not use test leads, probes or crocodile clips that are
dirty, damaged or have broken or cracked insulation.
Such accessories should immediately be removed and
repaired.
(4) Always disconnect the test leads before replacing the
internal fuse or the batteries. Always replace the fuse
or batteries with the type specified and ensure that they
are correctly fitted.
(5) Double check the switch setting and lead connections
before taking measurements.
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7. SPARES AND ACCESSORIES
Standard Kelvin Lead Set: DFK 0094
Carry Case: DFK 0064P
Instruction Manual: CMR 0073
(6) Do not touch exposed wiring, connections or other
‘live’ parts of an electrical circuit. If in doubt, check
the circuit first for voltage before touching it.
(7) This instrument should not be used in wet conditions.
NOTE: This instrument should only be used by a competent,
suitably trained person
Explanation Of Symbols Used
Caution, risk of electric shock.
Caution, refer to the instruction manual.
(6) Do not touch exposed wiring, connections or other
‘live’ parts of an electrical circuit. If in doubt, check
the circuit first for voltage before touching it.
(7) This instrument should not be used in wet conditions.
NOTE: This instrument should only be used by a competent,
suitably trained person
Explanation Of Symbols Used
Caution, risk of electric shock.
Caution, refer to the instruction manual.
7. SPARES AND ACCESSORIES
Standard Kelvin Lead Set: DFK 0094
Carry Case: DFK 0064P
Instruction Manual: CMR 0073
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2. GENERAL DESCRIPTION
The E1620 digital milli–ohmmeter is a hand–held, high current
instrument with which stable, accurate measurements of
resistance can be made over a wide range of values. Resolution
on the lowest range is 10µΩ and the highest range has a maximum
value of 20Ω. Measurements are displayed on a 3½ digit, custom
liquid crystal display with large digits. This instrument
incorporates a high efficiency converter which allows it to be
powered by either manganese alkali cells or rechargeable nickel–
cadmium cells. A hold function is incorporated in the display
circuit to assist in reducing the power consumption of this tester.
The instrument has two principle circuits; a high efficiency D.C.
converter and a digital D.C. milli–voltmeter. Employing feedback
techniques, the D.C. converter supplies a constant current to the
resistance being measured via the current terminals. Voltage drop
across this resistance is monitored by the milli–voltmeter via
the potential terminals. As the analogue to digital converter in
the milli–voltmeter utilises a ratiometric technique, the resistance
is measured precisely and is unaffected by variations of the test
current.
The E1620 has a custom, 3½ digit liquid crystal display with
18mm high digits which are readily viewed in most lighting
conditions. This display also indicates low battery voltage,
overrange and reverse polarity of load conditions. The decimal
point changes to correspond with the range selected. Two LED
indicators warn the operator that the test current is low or that
mains voltage is present on the input terminals.
Drop Test: IEC1010, Clause 8.4
Impact Test: IEC1010, Clause 8.2
Weight: 0.75kg (with batteries and leads)
6.3 Environmental
Operating Temperature
Range: -15ºC to +55ºC
Storage Temperature
Range: -20ºC to +65ºC
Humidity: 93% RH at +40ºC
Cold Temperature: IEC68-2-1
Dry Heat: IEC68–2–2
Damp Heat: IEC68–2–3
Drop Test: IEC1010, Clause 8.4
Impact Test: IEC1010, Clause 8.2
Weight: 0.75kg (with batteries and leads)
6.3 Environmental
Operating Temperature
Range: -15ºC to +55ºC
Storage Temperature
Range: -20ºC to +65ºC
Humidity: 93% RH at +40ºC
Cold Temperature: IEC68-2-1
Dry Heat: IEC68–2–2
Damp Heat: IEC68–2–3
2. GENERAL DESCRIPTION
The E1620 digital milli–ohmmeter is a hand–held, high current
instrument with which stable, accurate measurements of
resistance can be made over a wide range of values. Resolution
on the lowest range is 10µΩ and the highest range has a maximum
value of 20Ω. Measurements are displayed on a 3½ digit, custom
liquid crystal display with large digits. This instrument
incorporates a high efficiency converter which allows it to be
powered by either manganese alkali cells or rechargeable nickel–
cadmium cells. A hold function is incorporated in the display
circuit to assist in reducing the power consumption of this tester.
The instrument has two principle circuits; a high efficiency D.C.
converter and a digital D.C. milli–voltmeter. Employing feedback
techniques, the D.C. converter supplies a constant current to the
resistance being measured via the current terminals. Voltage drop
across this resistance is monitored by the milli–voltmeter via
the potential terminals. As the analogue to digital converter in
the milli–voltmeter utilises a ratiometric technique, the resistance
is measured precisely and is unaffected by variations of the test
current.
The E1620 has a custom, 3½ digit liquid crystal display with
18mm high digits which are readily viewed in most lighting
conditions. This display also indicates low battery voltage,
overrange and reverse polarity of load conditions. The decimal
point changes to correspond with the range selected. Two LED
indicators warn the operator that the test current is low or that
mains voltage is present on the input terminals.
The ranges are selected by a four–position rotary switch, and
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150Ω on 2 and 20Ω ranges
Battery: 6 off, AA size, manganese–alkali
or nickel cadmium cells
Battery Low Voltage: 6.7V
Battery Life: 2000 operations typical with
manganese–alkali batteries
550 operations typical with nickel
cadmium batteries
(an operation is assumed to be a
10–second measurement with a
2 minute display period)
Protection Fuse: 2 amp, FF, HBC, 5 X 20mm, DIN
Safety: LVD: To BS EN 61010-1
EMC: To BS EN 50081-1
BS EN 50082-1
6.2 Mechanical
Case Height: 190mm
Case Width: 90mm
Case Depth: 60mm
Bump Test: IEC68–2–29
Vibration Test: IEC1010, Clause 8.3
test is initiated by pressing the push–button, test switch.While
this switch is depressed the instrument takes a measurement,
and when it is released the instrument retains he last reading
taken for two minutes before automatically switching itself off.
The tester is packaged in a rugged, hand–held, moulded plastic
case. The standard accessory kit consists of a moulded
polypropylene carry case, a set of Kelvin leads and an instruction
manual.
3. FRONT PANEL LAYOUT
The ranges are selected by a four–position rotary switch, and
test is initiated by pressing the push–button, test switch.While
this switch is depressed the instrument takes a measurement,
and when it is released the instrument retains he last reading
taken for two minutes before automatically switching itself off.
The tester is packaged in a rugged, hand–held, moulded plastic
case. The standard accessory kit consists of a moulded
polypropylene carry case, a set of Kelvin leads and an instruction
manual.
3. FRONT PANEL LAYOUT
150Ω on 2 and 20Ω ranges
Battery: 6 off, AA size, manganese–alkali
or nickel cadmium cells
Battery Low Voltage: 6.7V
Battery Life: 2000 operations typical with
manganese–alkali batteries
550 operations typical with nickel
cadmium batteries
(an operation is assumed to be a
10–second measurement with a
2 minute display period)
Protection Fuse: 2 amp, FF, HBC, 5 X 20mm, DIN
Safety: LVD: To BS EN 61010-1
EMC: To BS EN 50081-1
BS EN 50082-1
6.2 Mechanical
Case Height: 190mm
Case Width: 90mm
Case Depth: 60mm
Bump Test: IEC68–2–29
Vibration Test: IEC1010, Clause 8.3
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4. PREPARATION FOR USE
The Metrohm E1620 is delivered in a shipping container. When
it is unpacked, it should be inspected for any visible signs of
damage, and the preliminary checks described in the operating
instructions should be performed to ensure that it is operating
correctly. If there is any sign of damage, or if the instrument
does not operate correctly, return it to the supplier.
This instrument can be powered from six, AA size, manganese–
alkali (MN1500, LR6) or nickel cadmium cells. During use, if
the battery low warning symbol appears on the display, then the
batteries should be replaced or recharged in the case of the nickel
cadmium batteries. It should be noted that nickel cadmium
batteries should be kept at +5ºC to +35ºC as their performance
deteriorates outwith the temperature band, even though they can
operate from -40ºC to +60ºC. Always check with the battery
manufacturer regarding their disposal.
It is recommended that the E1620 be calibrated every two years,
and that it should be carried out by the manufacturer or his
appointed agent. If the tester develops a fault, it should be
returned to the manufacturer for repair.
should be followed to access the fuse. The blown fuse should be
removed and replaced with a fuse of the correct type and rating.
5.9 Input Limits
The maximum continuous voltage that can be applied across the
potential terminals or across a potential and current terminal is
240V A.C. 240V A.C. applied across the current terminals will
cause the protection fuse to blow.
6. SPECIFICATION
6.1 Electrical
Ranges: 0 to 20mΩ in steps of 0.01mΩ
0 to 200mΩ in steps of 0.1mΩ
0 to 2Ω in steps of 1mΩ
0 to 20Ω in steps of 10mz
Accuracy: ±0.5% of reading ±2 digit (over
operating temperature range,
-15ºC to +55ºC, with standard
leads)
Test Current: 1A d.c. on 20mΩ range
0.1A d.c. on 200mΩ range
10mA d.c. on 2A and 20Ω ranges
Test Current Accuracy: ±10%
Max. Circuit Resistance: 1.2Ω on 20mΩ range
(with 9V battery voltage) 15Ω on 200mΩ range
removed and replaced with a fuse of the correct type and rating.
5.9 Input Limits
The maximum continuous voltage that can be applied across the
potential terminals or across a potential and current terminal is
240V A.C. 240V A.C. applied across the current terminals will
cause the protection fuse to blow.
6. SPECIFICATION
6.1 Electrical
Ranges: 0 to 20mΩ in steps of 0.01mΩ
0 to 200mΩ in steps of 0.1mΩ
0 to 2Ω in steps of 1mΩ
0 to 20Ω in steps of 10mz
Accuracy: ±0.5% of reading ±2 digit (over
operating temperature range,
-15ºC to +55ºC, with standard
leads)
Test Current: 1A d.c. on 20mΩ range
0.1A d.c. on 200mΩ range
10mA d.c. on 2A and 20Ω ranges
Test Current Accuracy: ±10%
Max. Circuit Resistance: 1.2Ω on 20mΩ range
(with 9V battery voltage) 15Ω on 200mΩ range
4. PREPARATION FOR USE
The Metrohm E1620 is delivered in a shipping container. When
it is unpacked, it should be inspected for any visible signs of
damage, and the preliminary checks described in the operating
instructions should be performed to ensure that it is operating
correctly. If there is any sign of damage, or if the instrument
does not operate correctly, return it to the supplier.
This instrument can be powered from six, AA size, manganese–
alkali (MN1500, LR6) or nickel cadmium cells. During use, if
the battery low warning symbol appears on the display, then the
batteries should be replaced or recharged in the case of the nickel
cadmium batteries. It should be noted that nickel cadmium
batteries should be kept at +5ºC to +35ºC as their performance
deteriorates outwith the temperature band, even though they can
operate from -40ºC to +60ºC. Always check with the battery
manufacturer regarding their disposal.
It is recommended that the E1620 be calibrated every two years,
and that it should be carried out by the manufacturer or his
appointed agent. If the tester develops a fault, it should be
returned to the manufacturer for repair.
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5. OPERATING INSTRUCTIONS
5.1 Preliminary Checks
(1) With the leads disconnected, select the 20mΩ range
and switch on the instrument by pressing the test switch
and holding it depressed.
(2) The low current warning lamp ‘I’ should light and the
LCD should indicate the overrange condition as shown
in Fig. 1.
Fig. 1
(3) If the warning lamp or the LCD display do not operate,
check that batteries have been correctly installed in the
instrument.
(4) On releasing the test switch, the reading should remain
on the LCD for about two minutes after which the
instrument will automatically switch off. Where
customer test leads are used, their connection to the
item to be tested should be as illustrated in Fig. 4.
to 10.40mΩ at 30ºC. Account should be taken of this effect in
making measurements.
When measuring the resistance of item, such as current shunts,
which have joints of dissimilar conductors, thermal EMFs can
affect the accuracy of the measurement. This condition can be
detected if the reading alters when the leads are reversed. To
compensate for this effect, the average of the two readings should
be taken as the true measurement.
5.7 Battery Replacement
If the ‘BAT’ symbol appears on the LCD during a test, testing
should be discontinued until the batteries are replaced or
recharged in the case of nickel–cadmium cells. Before accessing
the batteries, the test leads should be removed for safety reasons.
Access to the batteries is via the lid in the base of the instrument.
The two plastic screws should be loosened to allow the lid to be
removed. The discharged batteries can then be removed and
replaced with new or recharged batteries. The orientation of the
batteries should be as indicated by the polarity symbols in the
battery compartment. The lid can then be replaced and the plastic
screws tightened.
5.8 Fuse Replacement
Fuse protection is provided on the current terminals, C1 and
C2, and it is indicative of a blown fuse if the low current warning
lamp ‘I’ is lit and the resistance across terminals C1 and C2, is
less than 1Ω. The fuse is positioned in the battery terminal and
the same procedure, as was described in the previous section,
should be followed to access the fuse. The blown fuse should be
5. OPERATING INSTRUCTIONS
5.1 Preliminary Checks
(1) With the leads disconnected, select the 20mΩ range
and switch on the instrument by pressing the test switch
and holding it depressed.
(2) The low current warning lamp ‘I’ should light and the
LCD should indicate the overrange condition as shown
in Fig. 1.
Fig. 1
(3) If the warning lamp or the LCD display do not operate,
check that batteries have been correctly installed in the
instrument.
(4) On releasing the test switch, the reading should remain
on the LCD for about two minutes after which the
instrument will automatically switch off. Where
customer test leads are used, their connection to the
item to be tested should be as illustrated in Fig. 4.
to 10.40mΩ at 30ºC. Account should be taken of this effect in
making measurements.
When measuring the resistance of item, such as current shunts,
which have joints of dissimilar conductors, thermal EMFs can
affect the accuracy of the measurement. This condition can be
detected if the reading alters when the leads are reversed. To
compensate for this effect, the average of the two readings should
be taken as the true measurement.
5.7 Battery Replacement
If the ‘BAT’ symbol appears on the LCD during a test, testing
should be discontinued until the batteries are replaced or
recharged in the case of nickel–cadmium cells. Before accessing
the batteries, the test leads should be removed for safety reasons.
Access to the batteries is via the lid in the base of the instrument.
The two plastic screws should be loosened to allow the lid to be
removed. The discharged batteries can then be removed and
replaced with new or recharged batteries. The orientation of the
batteries should be as indicated by the polarity symbols in the
battery compartment. The lid can then be replaced and the plastic
screws tightened.
5.8 Fuse Replacement
Fuse protection is provided on the current terminals, C1 and
C2, and it is indicative of a blown fuse if the low current warning
lamp ‘I’ is lit and the resistance across terminals C1 and C2, is
less than 1Ω. The fuse is positioned in the battery terminal and
the same procedure, as was described in the previous section,
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(5) Connect the standard Kelvin lead set into the E1620.
One pair of leads should be connected into the C1 and
P1 sockets, and the other into the C2 and P2 sockets as
illustrated below in Fig. 2. Connect the two Kelvin
crocodile clips to a shorting bar.
Fig. 2
(6) Switch on the instrument by pressing the test switch
and holding it depressed.
(7) The low current warning lamp ‘I’ should not light and
the LCD should indicate zero within a digit.
(8) If the negative sign appears on the LCD, as shown in
Fig. 3, this indicates that the potential leads are reversed
in relation to the current leads. This is rectified by
reversing the potential leads to the sockets P1 and P2
Current Leads
1. Shrouded, 4mm, safety plugs are
required at one end of each lead as
before.
2. Insulated, 16/0.2mm, tinned copper
wire is recommended.
3. The length of these two leads should
be chosen so that the overall lead
resistance is less than 1Ω.
Fig. 4
5.6 Thermal Effects
Temperature can have a significant effect on the performance of
this instrument due to the temperature coefficient of resistance
and thermal EMFs across connections of dissimilar conductors.
Most conductors have a large temperature coefficient of
resistance, e.g. 0.4%/ºC for copper. As an example, a copper
conductor that has a resistance of 10.00mΩ at 20ºC will increase
Current Leads
1. Shrouded, 4mm, safety plugs are
required at one end of each lead as
before.
2. Insulated, 16/0.2mm, tinned copper
wire is recommended.
3. The length of these two leads should
be chosen so that the overall lead
resistance is less than 1Ω.
Fig. 4
5.6 Thermal Effects
Temperature can have a significant effect on the performance of
this instrument due to the temperature coefficient of resistance
and thermal EMFs across connections of dissimilar conductors.
Most conductors have a large temperature coefficient of
resistance, e.g. 0.4%/ºC for copper. As an example, a copper
conductor that has a resistance of 10.00mΩ at 20ºC will increase
(5) Connect the standard Kelvin lead set into the E1620.
One pair of leads should be connected into the C1 and
P1 sockets, and the other into the C2 and P2 sockets as
illustrated below in Fig. 2. Connect the two Kelvin
crocodile clips to a shorting bar.
Fig. 2
(6) Switch on the instrument by pressing the test switch
and holding it depressed.
(7) The low current warning lamp ‘I’ should not light and
the LCD should indicate zero within a digit.
(8) If the negative sign appears on the LCD, as shown in
Fig. 3, this indicates that the potential leads are reversed
in relation to the current leads. This is rectified by
reversing the potential leads to the sockets P1 and P2
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(vi) Testing and maintenance of switchboard/ sub–
station equipment on such items as fuses,
joints, contacts and bonds.
5.5 Customer Test Leads
The Kelvin crocodile clips supplied with the instrument are
suitable for connecting to conductors up to 15mm in diameter
or bus bars 15mm thick. There will be, however, instances where
the item being tested requires larger jaws, and the user is advised
to make up his own leads. Furthermore, there will be occasions
when longer leads are required due to the geometry of the item
being tested. The following guidance notes should assist in the
assembly of such leads:
Potential Leads
1. Shrouded, 4mm, safety plugs are
required at one end of each lead for
connection to the E1620 measuring
sockets.
2. Insulated, 16/0.2mm, tinned copper
wire is recommended.
3. The two potential leads should be the
same length to minimise inaccuracies
due to unbalance.
4. For practical reasons, the lead length
should be as short as possible to
minimise pick up.
Fig. 3
(9) If the ‘BAT’ symbol appears on the LCD during these
checks, as shown in Fig. 3, the batteries require to be
replaced or recharged. Follow the instructions for
replacing batteries outlined in the proceeding section.
5.2 Precautions
(1) Always ensure that the circuit to be measured is
switched off, isolated and completely de–energised
before connecting the test leads.
(2) If it is probable that the instrument’s protection has been
impaired due to electrical, mechanical or environmental
damage, it must not be used. It should be returned to
the manufacturer or his appointed
agent for checking and repair.
(3) To prevent damage to the liquid crystal display, the
minimum storage temperature of -20ºC must be
observed. It should also be noted that below 0ºC the
operation of this display will be sluggish.
(4) If the exterior of the instrument requires cleaning, it
should be done with a sponge and a mild solution of
Fig. 3
(9) If the ‘BAT’ symbol appears on the LCD during these
checks, as shown in Fig. 3, the batteries require to be
replaced or recharged. Follow the instructions for
replacing batteries outlined in the proceeding section.
5.2 Precautions
(1) Always ensure that the circuit to be measured is
switched off, isolated and completely de–energised
before connecting the test leads.
(2) If it is probable that the instrument’s protection has been
impaired due to electrical, mechanical or environmental
damage, it must not be used. It should be returned to
the manufacturer or his appointed
agent for checking and repair.
(3) To prevent damage to the liquid crystal display, the
minimum storage temperature of -20ºC must be
observed. It should also be noted that below 0ºC the
operation of this display will be sluggish.
(4) If the exterior of the instrument requires cleaning, it
should be done with a sponge and a mild solution of
(vi) Testing and maintenance of switchboard/ sub–
station equipment on such items as fuses,
joints, contacts and bonds.
5.5 Customer Test Leads
The Kelvin crocodile clips supplied with the instrument are
suitable for connecting to conductors up to 15mm in diameter
or bus bars 15mm thick. There will be, however, instances where
the item being tested requires larger jaws, and the user is advised
to make up his own leads. Furthermore, there will be occasions
when longer leads are required due to the geometry of the item
being tested. The following guidance notes should assist in the
assembly of such leads:
Potential Leads
1. Shrouded, 4mm, safety plugs are
required at one end of each lead for
connection to the E1620 measuring
sockets.
2. Insulated, 16/0.2mm, tinned copper
wire is recommended.
3. The two potential leads should be the
same length to minimise inaccuracies
due to unbalance.
4. For practical reasons, the lead length
should be as short as possible to
minimise pick up.
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detergent and water. Other chemical cleaning agents
must not be used.
5.3 Taking Measurements
(1) Perform the preliminary checks previously described,
and ensure that the precautions listed are observed.
(2) Connect the standard Kelvin test leads to the instrument
as illustrated in Fig. 2 and check that the resistance to
be measured is isolated from the supply and completely
de–energised. Connect the Kelvin crocodile clips across
the resistance to be measured.
(3) If the voltage warning lamp lights ( ), there is a
dangerous voltage across the resistance to be measured.
The source of this dangerous voltage must be isolated
before proceeding. It should be noted that the voltage
warning lamp does not indicate for dangerous voltages
between the resistance being measured and earth/
ground. Only good working practises will eliminate
such a source of danger.
(4) Set the rotary selector switch on the E1620 to the
desired range. Press the test switch and hold it depressed
until a steady reading is obtained on the display. Release
the test switch. The reading will be retained on the
display for a further two minutes.
(5) If the low current warning lamp ‘I’ lights while the test
switch is depressed, the reading obtained must not be
accepted as there will be inaccuracies due to the
resistance between the current terminals, C1 and C2,
being too great. This problem can usually be
circumvented by selecting a higher measurement range
or by reducing the resistance of the leads to the current
terminals.
(6) If the instrument indicates the over–range condition as
shown in Fig. 1, then a higher measurement range
should be selected.
5.4 Applications
The E1620 digital milli–ohmmeter, with its measuring range of
10µΩ to 19.99Ω, is suitable for a wide range of applications
such as:
(i) Measuring the winding resistance of electric
motors, generators and transformers.
(ii) Bond testing in aircraft, mines, railways, ships
anddomestic and industrial wiring
installations.
(iii) Ring main continuity testing in industrial and
domestic wiring installations.
(iv) Measuring resistance in electronic equipment
on such items as resistors, shunts, PCB
tracks, switch and relay contacts, etc.
(v) Checking compression joints on overhead
lines.
accepted as there will be inaccuracies due to the
resistance between the current terminals, C1 and C2,
being too great. This problem can usually be
circumvented by selecting a higher measurement range
or by reducing the resistance of the leads to the current
terminals.
(6) If the instrument indicates the over–range condition as
shown in Fig. 1, then a higher measurement range
should be selected.
5.4 Applications
The E1620 digital milli–ohmmeter, with its measuring range of
10µΩ to 19.99Ω, is suitable for a wide range of applications
such as:
(i) Measuring the winding resistance of electric
motors, generators and transformers.
(ii) Bond testing in aircraft, mines, railways, ships
anddomestic and industrial wiring
installations.
(iii) Ring main continuity testing in industrial and
domestic wiring installations.
(iv) Measuring resistance in electronic equipment
on such items as resistors, shunts, PCB
tracks, switch and relay contacts, etc.
(v) Checking compression joints on overhead
lines.
detergent and water. Other chemical cleaning agents
must not be used.
5.3 Taking Measurements
(1) Perform the preliminary checks previously described,
and ensure that the precautions listed are observed.
(2) Connect the standard Kelvin test leads to the instrument
as illustrated in Fig. 2 and check that the resistance to
be measured is isolated from the supply and completely
de–energised. Connect the Kelvin crocodile clips across
the resistance to be measured.
(3) If the voltage warning lamp lights ( ), there is a
dangerous voltage across the resistance to be measured.
The source of this dangerous voltage must be isolated
before proceeding. It should be noted that the voltage
warning lamp does not indicate for dangerous voltages
between the resistance being measured and earth/
ground. Only good working practises will eliminate
such a source of danger.
(4) Set the rotary selector switch on the E1620 to the
desired range. Press the test switch and hold it depressed
until a steady reading is obtained on the display. Release
the test switch. The reading will be retained on the
display for a further two minutes.
(5) If the low current warning lamp ‘I’ lights while the test
switch is depressed, the reading obtained must not be
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