Hioki 3151 User manual

3151
EARTH HiTESTER
INSTRUCTION MANUAL

Contents
Introduction i
Inspection i
Safety Notes ii
Notes on Use vi
Chapter 1 Outline 1
1.1 Product Outline 1
1.2 Features 2
1.3 Names and Functions of Parts 4
Chapter 2 Specifications 7
2.1 General Specifications 7
2.2 Measurement Range and Tolerances 9
Chapter 3 Technical Information 11
3.1 Earthing Resistance 11
3.2 Measurement Principle 13
Chapter 4 Measurement Procedure 15
4.1 Preparations 16
4.2 Normal Measurement (3-Pole Method) 17
4.3 Simplified Measurement (2-Pole Method) 22
4.4 Using the Earthing Net 28
4.5 Measurement Precautions and Hints 29
Chapter 5 Maintenance and Service 35
5.1 Attaching the Hand Strap 35
5.2 Changing the Batteries 36
5.3 Cleaning the Unit 38
5.4 Service 38

i
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Introduction
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Introduction
Inspection
Thank you for purchasing the HIOKI"3151
EARTH HiTESTER." To obtain maximum
performance from the instrument, please read
this manual first, and keep it handy for future
reference.
When you receive the instrument, inspect it
carefully to ensure that no damage occurred
during shipping. In particular, check the
accessories, panel switches, and connectors. If
damage is evident, or if it fails to operate
according to the specifications, contact your
dealer or Hioki representative.
Accessories
9214 AUXILIARY EARTHING RODS (two)
9215 MEASURING CABLE
(black 5 m, yellow 10 m, red 20 m)
9216 CABLE WINDER (with 9215) (three)
9393 CARRYING CASE
Hand strap
Instruction manual
R6P Manganese batteries (six)

ii
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Safety Notes
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DANGER
This instrument is designed to comply with IEC
61010 Safety Standards, and has been thoroughly
tested for safety prior to shipment. However,
mishandling during use could result in injury or
death, as well as damage to the instrument. Be
certain that you understand the instructions and
precautions in the manual before use. We
disclaim any responsibility for accidents or
injuries not resulting directly from instrument
defects.
Safety Notes
This manual contains information and
warnings essential for safe operation of the
instrument and for maintaining it in safe
operating condition. Before using the
instrument, be sure to carefully read the
following safety notes.

iii
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Safety Notes
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The symbol printed on the
instrument indicates that the user
should refer to a corresponding topic in
the manual (marked with the
symbol) before using the relevant
function.
In the manual, the symbol indicates
particularly important information that
the user should read before using the
instrument.
Indicates a double-insulated device.
Indicates AC (Alternating Current).
DANGER
Indicates that incorrect operation
presents an extreme hazard that could
result in serious injury or death to the
user.
WARNING
Indicates that incorrect operation
presents a significant hazard that could
result in serious injury or death to the
use.
CAUTION
Indicates that incorrect operation
presents a possibility of injury to the
user or damage to the instrument.
NOTE Indicates advisory items related to
performance or correct operation of the
instrument.
Safety Symbols
The following symbols in this manual indicate
the relative importance of cautions and warnings.

iv
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Safety Notes
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Overvoltage categories (CAT)
This instrument complies with CAT II safety
requirements.
To ensure safe operation of measurement
instruments, IEC 60664 establishes safety
standards for various electrical environments,
categorized as CAT I to CAT IV, and called
overvoltage categories. These are defined as
follows.
CAT I : Secondary electrical circuits
connected to an AC electrical outlet
through a transformer or similar
device.
CAT II : Primary electrical circuits in
equipment connected to an AC
electrical outlet by a power cord
(portable tools, household appliances,
etc.)
CAT III : Primary electrical circuits of heavy
equipment (fixed installations)
connected directly to the distribution
panel, and feeders from the
distribution panel to outlets.
CAT IV : The circuit from the service drop to
the service entrance, and to the
power meter and primary overcurrent
protection device (distribution panel).

v
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Safety Notes
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Higher-numbered categories correspond to
electrical environments with greater momentary
energy. So a measurement device designed for
CAT III environments can endure greater
momentary energy than a device designed for
CAT II.
Using a measurement instrument in an
environment designated with a higher-
numbered category than that for which the
instrument is rated could result in a severe
accident, and must be carefully avoided.

vi
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Notes on Use
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DANGER
When measuring earthing resistance, a voltage
of maximum 50 Vrms exists across the
measurement terminals E - C(H). Take proper
precautions against electric shock.
When performing a simplified measurement (2-
pole method) with the instrument connected to
the earth side of a household power supply (AC
outlet), take proper precautions against electric
shock.
Notes on Use
Follow these precautions to ensure safe
operation and to obtain the full benefits of the
various functions.

vii
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Notes on Use
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WARNING
Do not allow the instrument to get wet, and do
not take measurements with wet hands. This may
cause an electric shock. Take appropriate care
when using the instrument outdoors.
Do not use the instrument where it may be
exposed to corrosive or combustible gases. The
instrument may be damaged or cause an
explosion.
Do not power the instrument from sources other
than batteries, to prevent damage and the risk of
electric shock.
Before using the instrument, make sure that the
insulation on the measuring cable is undamaged
and that no bare conductors are improperly
exposed. Using the instrument in such conditions
could cause an electric shock, so contact your
dealer or Hioki representative for replacements.
(Model 9215).

viii
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Notes on Use
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CAUTION
Do not store or use the instrument where it could
be exposed to direct sunlight, high temperature or
humidity, or condensation. Under such conditions,
the instrument may be damaged and insulation
may deteriorate so that it no longer meets
specifications.
Although this instrument is dust resistant, it is not
completely dust- or waterproof. To prevent possible
damage, avoid using in dusty or wet environments.
To avoid damage to the instrument, protect it from
physical shock when transporting and handling. Be
especially careful to avoid physical shock from
dropping.

1
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Chapter 1 Outline
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Chapter 1
Outline
1.1 Product Outline
The earthing (grounding) of electrical
equipment is essential in maintaining safety
and protecting lives, as well as preventing
damage to equipment.
This instrument uses the AC phase differential
system to measure earthing resistance. This
assures accurate measurements unaffected by
earth voltage and auxiliary earthing resistance.

2
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Chapter 1 Outline
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1.2 Features
(1) High performance
Performance of this instrument surpasses the
requirements of the Japanese standard JISC-
1304-1995 and complies with the safety
standard IEC 61010.
(2) Wide measurement range
Measurement scope was extended to 115% of
the earthing resistance measurement range.
This is useful especially in the 10 Ωand
100 Ωmeasurement modes which are
important for earthing evaluation during
electrical installation work.
(3) Auxiliary earthing resistance check function
Auxiliary earthing resistance can be checked
for each pole, in order to evaluate possible
influences upon the measurement.
(4) Switchable measurement frequency
Measurement frequency can be changed by the
user, to minimize the influence of harmonic
earth voltage and to assure stable
measurement.
(5) Simplified measurement function
Simplified earthing resistance measurement is
possible using the earth of an AC outlet.

3
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Chapter 1 Outline
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(6) Over-voltage protection and warning buzzer
When an AC outlet is used for simplified
measurement and a voltage is input by
mistake, the protection circuit is activated and
a warning tone is heard.
(7) Semi-dust-proof construction
Measurement switches, indicators and other
moving parts are designed to withstand use in
tough environments.
(8) Easy to use
The supplied carrying case is designed to hold
the instrument and all accessories. A cable
winder is standard, making it easy to deploy
and store measurement leads.

4
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Chapter 1 Outline
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Front View
12
3
4
5
6
7
8
9
10
11 12 13
14
1.3 Names and Functions of Parts
① Measurement button (PRESS ON)
Press this button for earthing resistance
measurement, auxiliary earthing resistance
check, and battery check.
② Range selector
Serves to switch the instrument to battery
check, earth voltage measurement, auxiliary
earthing resistance check, and earthing
resistance measurement.
③ 2/3 pole measurement selector (TERMINALS)
Serves to switch between 2-pole measurement
(simplified measurement) and 3-pole
measurement. Also serves to switch the
measurement frequency (a/b) to reduce the
influence of harmonic earth voltage.

5
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Chapter 1 Outline
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④ Resistance dial
The measured resistance value can be read
from this dial.
⑤Dialknob
⑥ Galvanometer
⑦ Battery effective range
⑧ Auxiliary earthing resistance effective range
⑨ Earth voltage scale
⑩ADJUST:Zeroadjustment
⑪ E: Earth terminal
This terminal is to be connected to the earth of
the measurement object.
⑫ P (S): Probe terminal
Terminal for potential detection
⑬ C (H): Auxiliary earthing terminal
This terminal supplies measurement current.
⑭ Explanation label
Contains brief instructions and instrument
specifications.

6
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Chapter 1 Outline
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Rear View 15
16
⑮ Fixing screw on the battery cover
⑯ Battery cover

7
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Chapter 2 Specifications
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Operating system AC potentiometer
Display Method Resistance indication on meter with
linear scale galvanometer
Open circuit voltage 50 V AC max
Measurement current 15 mA AC max (using the 2-pole
method: 3 mA AC max)
Measurement
frequency
575 Hz (during setting to 2a or 3a)
600 Hz (during setting to 2b or 3b)
Operating
temperature and
humidity range
0to40 (32 to 104 ),
80% RH or less (with no condensation)
Storage temperature
and humidity range
-10 to 50 (14 to 122 ),
80% RH or less (with no condensation)
Usage range Instrument is designed for earthing
resistance measurements in locations up to
a height of 3,000 meters (except farms)
Power supply Six R6P manganese batteries or
six LR6 alkaline batteries
Rated supply voltage: 1.5 V x 6
Maximum rated
power
2.5 VA max
Chapter 2
Specifications
2.1 General Specifications

8
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Chapter 2 Specifications
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Battery Life More than 500 times (R6P in use) or
more than 1400 (LR6 in use)
(30-second measurement/30-second
pause cycle)
Overvoltage
protection
250 VAC for one minute
between E-P (S) and E-C (H) terminals
Insulation resistance 100 MΩor more/500 V DC
between electric circuit and case
Dielectric voltage 3000 V AC for one minute
between electric circuit and case
External dimensions Approx. 164W x 119H x 88D mm
(6.46W" x 4.37H" x 3.47D")
(excluding protrusion)
Mass Approx. 800 g (28.2oz.) (instrument only)
Accessories 9214 AUXILIARY EARTHING ROD
9215 MEASURING CABLE
(black 5m, yellow 10 m,
red 20 m each one,
9216 CABLE WINDER x 3)
9393 CARRYING CASE
R6P manganese battery x 6
Instruction manual, Hand strap
Option 9050 EARTH NETS 30 x 30cm
Standards applying
Earthing resistance
measurement
Safety
EMC
Environment
protection
JIS C1304-1995
EN61557-5:1997
JIS C1004-1996
EN61010-1:2001
Pollution Degree 2, Measurement
Category II (anticipated transient
overvoltage 500 V)
EN61010-2-031:1994
EN61326:1997+A1:1998+A2:2001
EN60529:1991 "IP40"
JIS C920-1993