Iskra MI7054 User manual

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OPERATING INSTRUCTIONS
ANALOG MULTIMETER
MI7054

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TABLE OF CONTENTS
1. Safety features and precautions 3
2. description 4
3. Characteristic values 4
4. measuring ranges and characteristic values 4
4.1 Voltage 4
4.2 Current 4
4.3 Resistance 5
5. ACCURACY AND INFLUENCING QUANTITIES 5
5.1 Accuracy under Reference Conditions 5
5.2 Frequency Influence 5
5.3 Temperature Influence 5
6. overload protection 5
7. battery for resistance measurements 5
8. OPERATING INSTRUCTIONS 6
9. MEASUREMENTS 6
9.1 Direct and Alternating Voltage Measurements 7
9.2 Direct and Alternating Current Measurements 7
9.3 Resistance Measurement 7
10. MAINTENANCE 8
10.1 Replacing the Battery 8
10.2 Cleaning 8
11. FUSING 8

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1. SAFETY FEATURES AND PRECAUTIONS
You have selected an instrument which provides you with a high level of safety. The multime-
ter is manufactured and tested in accordance with safety regulations IEC 61010–1 / DIN EN
61010–1 / VDE 0411–1. When used for its intended purpose, safety of the operator, as well as
that of the instrument, is assured. Their safety is however not guaranteed, if the instrument is
used improperly or handled carelessly. In order to maintain flawless technical safety condi-
tions, and to assure safe use, it is imperative that you read the operating instructions thor-
oughly and carefully before placing your instrument into service, and that you follow all instruc-
tions contained therein. The instrument is equipped with a circuit breaker for your safety and to
protect the multimeter. It interrupts the current circuit if overload occurs during measurement.
Observe the following safety precautions:
•The instrument may only be operated by persons who are capable of recognizing contact
hazards and taking the appropriate safety precautions. Contact hazards exist anywhere,
where voltages of greater than 30 V RMS may occur.
•Avoid working alone when taking measurements which involve contact hazards. Be certain
that a second person is present.
•The maximum allowable voltage between the voltage terminals and ground is 600 V~ cate-
gory II, or 300 V~ category III.
•Nominal voltage at the electrical system may not exceed the following values:
Between phase and neutral conductor 600 V
In 4-wire 3-phase systems 400 V between phase conductors
In 3-wire 3-phase systems 400 V between phase conductors
•The current measuring ranges are equipped with automatic switches. The maximum al-
lowable voltage for the current measuring circuit (= rated voltage of the fuse) is 240 V~ /
50V=in the “mA” and “A” ranges. Make sure that heavy current measuring circuits are pre-
fused with a 20 A fuse.
•Be prepared for the occurrence of unexpected voltages at devices under test (e.g. defective
devices). For example, capacitors can be dangerously charged.
•Make certain that the measurement cables are in flawless condition, e.g. no damage to in-
sulation, no interruptions in cables or plugs etc.
•No measurements may be made with this instrument in electrical circuits with corona dis-
charge (high-voltage).
•Special care is required when measurements are made in HF electrical circuits. Dangerous
pulsating voltages may be present.
•Measurements under moist ambient conditions are not permitted.
•Be absolutely certain that the measuring ranges are not overloaded beyond their allowable
capacities. Limit values can be found in the Measuring Ranges table in chapter 24, “Charac-
teristic Values”.
Meanings of symbols on the instrument
Warning concerning a point of danger (Attention: observe documentation!)
Ground
Continuous, doubled or reinforced insulation
Overvoltage category II or III device
Indicates EC conformity
CAT II / III
CC

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2. DESCRIPTION
The MI7054 multimeter has been designed for measurements in industry, for training and in
the commercial trades. Its greatest advantage is protection: The current measuring ranges are
protected against overload with an electromagnetic protective relay (AUTO-FUSE), resistance
ranges are protected with a PTC thermistor, and the voltage measuring ranges are protected
through the use of adequately dimensioned electrical components.
3. CHARACTERISTIC VALUES
•Scale Length: approx. 87 mm
•Pointer Stop: 0 ... 100 °∠
•Accuracy Class: 2.5
•Dimensions: 104 x 143 x 40 mm
•Weight: approx. 300 g
Safety Regulations in accordance with IEC 61010-1
Operating Voltage Overvoltage Category Fouling Factor Measuring Function
600 V II 2 V
300 V III 2 V
240 V~ / 50 V= II 2 A
Electromagnetic Compatibility (EMC)
Interference immunity and interference emission per EN 61326-1
Protection
Housing: IP 40 EN 60529
4. MEASURING RANGES AND CHARACTERISTIC VALUES
4.1 Voltage
DC AC
Measuring Range Internal Resistance Measuring Range Internal Resistance
30 V 30 kΩ30 V 32 kΩ
300 V 300 kΩ300 V 380 kΩ
600 V 600 kΩ600 V 780 kΩ
4.2 Current *
)Current > 10 A max. 5 min.
DC AC
Current Voltage Drop Current Voltage Drop
0.3 A 140 mV 0.3 A 140 mV
3 A 320 mV 3 A 320 mV
15 A*)915 mV 15 A 915 mV

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4.3 Resistance
Measuring
Range
Scale Range and Value
at Scale Center
Measuring Cur-
rent Imax
2)
, prox. Battery Voltage
Ωx 1 1 Ω... 30 Ω... 3 kΩ50 mA
Ωx 10 10 Ω... 300 Ω... 30 kΩ6 mA 1.5 V
Ωx 100 100 Ω... 3 kΩ... 300 kΩ0.6 mA (IEC R6)
2) With 1.5 V battery voltage
5. ACCURACY AND INFLUENCING QUANTITIES
5.1 Accuracy under Reference Conditions
Current, voltage and resistance accuracy under reference conditions:
Class 2.5 for DC
Class 2.5 for AC
Class 2.5 for Ω(with reference to a scale length of 87 mm)
Reference Conditions
Ambient Temperature 23°C ±3°
Position of Use horizontal
Frequency 45 ... 65 Hz
Waveshape for AC: sine (max. deviation: 1%)
5.2 Frequency Influence
•±2.5% of scale length in all measuring ranges, and in a frequency range of 30 Hz …1 kHz
5.3 Temperature Influence
±2.5% of scale length with a change in ambient temperature of 10 K within a temperature
range of 0...40 °C
6. OVERLOAD PROTECTION
•The voltage ranges are protected against overload to 600 VAC and 600 VDC with PTC ther-
mistors, and by means of adequately dimensioned electrical components.
•The current ranges are protected against overload to 240 VAC or 50 VDC with an electro-
magnetic interrupter (AUTO-FUSE). Current and resistance ranges are additionally pro-
tected against voltages of up to 500 VAC and 500 VDC with a slow-blow fuse (16 A / 500 V),
in order to prevent danger resulting from inadvertent measurement beyond the specified
category. However, internal components may be destroyed in such cases!
•The resistance ranges are protected against overload to 250 VAC with PTC thermistors and
by means of adequately dimensioned electrical components. The time limit for measure-
ments at this level of overloading is approximately 30 seconds.
7. BATTERY FOR RESISTANCE MEASUREMENTS
1 ea. 1.5 V IEC LR6 or LR6. We recommend the use of leak-proof batteries.

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8. OPERATING INSTRUCTIONS
Initial Start-Up
The instructions included below must be followed in order to assure error-free, safe use of the
instrument:
The instrument must be in the horizontal position during the performance of measurements.
The battery must be inserted into the instrument for resistance measurements. First remove
the battery compartment cover from the instrument, and then insert the battery (IEC LR6). The
battery supplies auxiliary voltage for resistance measurements. Make sure that the battery
contacts are clean and mechanically secure. The battery level can be checked by setting the
measuring range switch to the “Ωx 1” position and then shorting the ⊥and Ωmeasurement
cables. Set the needle to full-scale deflection with the potentiometer knob (0 on the Ωscale). If
the needle can no longer bet set to full-scale deflection, or if indication is erratic, the battery
must be replaced.
The measurement cables must be disconnected from the measuring circuit at
all poles before opening the instrument!
Make sure that the needle is adjusted to zero with the instrument switched off, and correct if
required (with the adjusting screw at the back). Discharge any static electrical charging with a
damp cloth after cleaning the glass face plate.
1. Set the measuring range selector switch to the desired position. Always start with the larg-
est measuring range for current and voltage measurements, and then switch to the appro-
priate, smaller measuring range. Do not interrupt the measuring circuit during switching.
Observe maximum measuring limits and correct polarity at the measurement connections.
After the measurement has been completed, return the measuring range selector switch to
the largest voltage measuring range.
2. Full scale deflection to “0 Ω” for resistance measurements, short jacks ⊥and Ωwith a
measurement cable.
3. Observe detailed instructions in the following chapter for initial start-up.
9. MEASUREMENTS
Make sure that the circuit breaker is active and that the internal voltage
measuring circuit functions correctly before performing voltage measure-
ments at dangerous contact voltages in accordance with chapter 9.1. The is
best assured by performing a resistance measurement in accordance with
chapter 9.5 (zero point test)!
cMeasuring range selector switch
dMeasurement input jacks
eSnap catch
fBattery
gReset switch for breaker (AUTO-FUSE)
hRotary knob for pointer adjustment to 0 Ω
(full scale deflection)

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9.1 Direct and Alternating Voltage Measurements
Direct Voltage Measurements to 600 V
Measuring range selector switch:
600V…30V= or V~
Measured value: can be read from the V (A)
scale
9.2 Direct and Alternating Current Measurements
In the event of incorrect connection (inadvertent application of voltage to
max. 50 V DC or 240 V AC), the protective relay is switched off. The “AUTO-
FUSE” breaker jumps to the green field. After the error has been eliminated,
the slide must be set to the white field in order to perform further meas-
urements.
The allowable measuring duration for current measurements of greater
than 10 A is limited to max. 5 minutes due to heating-up at the measure-
ment jacks. The cut-off relay tends to hum at these higher current values!
The MI7054 must be connected to the consumer in series. For reasons of safety, voltage to
earth may not exceed 240 V~ or 50 V= for installation category II.
Measuring range selector switch: 15 A ... 0.3 A= or A~
Measured value: read from the corresponding V or A scale
Measured values >10 A max. 5 minutes!
9.3 Resistance Measurement
Only voltage-free objects may be measured (resistors, capacitors). Interfer-
ence voltages distort measurement results.
In the event of incorrect connection (e.g. to 230 V AC), the pointer moves
towards “∞” after a few seconds. Overload duration is max. 30 s.
Resistance measurement is performed with direct voltage from the installed 1.5 V battery. Full
scale deflection to “0 Ω” should be checked as required during long duration resistance meas-
urements. Deflection should also be checked and corrected if necessary after switching to
other resistance measuring ranges.

Printed in Slovenia
•
Subject to change without notice •Version 02 / Sep. 2006
•
22.600.718
Plus pole to ⊥
Minus pole to Ω
Measuring range switch: Ωx 1 ... Ωx 100
Measured value: read from the Ωscale
After eliminating an overload, the MI7054 requires approximately 4 minutes before it is once
again able to perform measurements with the specified levels of accuracy.
The battery is discharged rapidly in the Ωx 1 measuring range. Limit measurements in
this range to the shortest possible duration. Connect measurement cables to jacks ⊥and
Ω, and set the display to “0 Ω” with the rotary knob (Ω).
10. MAINTENANCE
No special care or maintenance is required. The battery level should be checked from time to
time. Discharged or electrolyzed batteries must be removed from the battery compartment.
The battery contacts should be kept clean, and reliable contact pressure must be assured. If
the MI7054 remains unused for a lengthy period of time, remove the battery from the battery
compartment as a precaution.
10.1 Replacing the Battery
CAUTION: The measurement cables must be disconnected from the measuring circuit
at all poles before opening the instrument!
Press in the tab at the housing rear panel with a suitable tool and remove the housing bottom.
Insert the battery into the connectors located in the battery compartment.
Set the housing bottom back into place and press both housing parts together until they snap
into place.
10.2 Cleaning
A soft cloth which has been slightly dampened with alcohol and a brush are required for clean-
ing. Electrical charges at the glass face plate may influence measurements. These can be
eliminated with a damp cloth. Stubborn contamination can be removed with a cloth which has
been dampened with alcohol. No other solvents may be used.
11. FUSING
Fuse specification: 6.3 *32 mm, T 16A/500V
This fuse serves as an emergency fuse in the event of operator error. If the fuse blows, dam-
age to the circuit may not be ruled out. Inspection is required at our service department in such
cases. Any necessary repairs are not covered by the guarantee!