IEC TR 61243-6:2017
(Main)Live working - Voltage detectors - Part 6: Guidelines on non-contact voltage detectors (NCVD) for use at nominal voltages above 1 kV AC
Live working - Voltage detectors - Part 6: Guidelines on non-contact voltage detectors (NCVD) for use at nominal voltages above 1 kV AC
IEC TR 61243-6:2017(E) is applicable to portable non-contact voltage detectors (NCVD) with built-in power source, to be used to indicate the presence or the absence of the operating voltage on electrical systems for nominal voltages above 1 kV AC and frequencies of 16 2/3 Hz, 50 Hz and/or 60 Hz. This document describes only devices, and their behaviour, using electric field and voltage gradient detection principles even if other principles could be used. It provides performance guidelines, recommendations for use and recommended minimum criteria for selection.
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IEC TR 61243-6 ®
Edition 1.0 2017-03
TECHNICAL
REPORT
colour
inside
Live working – Voltage detectors –
Part 6: Guidelines on non-contact voltage detectors (NCVD) for use at nominal
voltages above 1 kV AC
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IEC TR 61243-6 ®
Edition 1.0 2017-03
TECHNICAL
REPORT
colour
inside
Live working – Voltage detectors –
Part 6: Guidelines on non-contact voltage detectors (NCVD) for use at nominal
voltages above 1 kV AC
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.260; 29.240.20; 29.260.99 ISBN 978-2-8322-3903-2
– 2 – IEC TR 61243-6:2017 © IEC 2017
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 The principles of an NCVD . 11
4.1 NCVD designed to work at a distance without any contact . 11
4.2 NCVD designed to work with reference points . 13
4.2.1 General . 13
4.2.2 NCVD designed to work with one reference point . 14
4.2.3 NCVD designed to work with two reference points . 15
5 Different designs of non-contact voltage detectors . 17
6 Limitations and recommendations of use for each type of NCVD . 19
6.1 Principal limitations . 19
6.2 Recommendations for the selection, calibration and use of NCVD . 19
6.2.1 Selection of the appropriate type of NCVD . 19
6.2.2 Calibration of the selected device . 20
6.2.3 Use of the selected device . 20
7 Recommended requirements . 21
7.1 General . 21
7.2 Recommended general requirements . 21
7.2.1 Safety . 21
7.2.2 Indication . 21
7.2.3 Electromagnetic compatibility (EMC) . 21
7.3 Recommended functional requirements . 22
7.3.1 Clear indication . 22
7.3.2 Clear perceptibility . 25
7.3.3 Temperature and humidity dependence of the indication . 26
7.3.4 Frequency dependence . 26
7.3.5 Response time . 26
7.3.6 Power source dependability . 26
7.3.7 Testing element . 26
7.3.8 Non response to DC voltage (static electric field) . 27
7.3.9 Immunity to electrostatic discharges . 27
7.3.10 Time rating . 27
7.4 Electrical requirements . 27
7.4.1 Insulating material . 27
7.4.2 Protection against bridging for Type 3 only . 27
7.4.3 Resistance against sparking . 28
7.4.4 Resistive (impedance) element of Type 5 only . 28
7.5 Recommendations for mechanical performance . 28
7.5.1 General . 28
7.5.2 Design . 28
7.5.3 Dimensions and construction . 28
7.5.4 Degree of protection provided by enclosure . 30
7.5.5 Grip force and deflection. 30
7.5.6 Vibration drop and shock resistance . 31
7.6 Markings . 31
7.7 Instructions for use . 31
Annex A (informative) General considerations about voltage detection . 32
A.1 General . 32
A.2 Principles of functioning of voltage detectors . 32
A.2.1 Basic analysis. 32
A.2.2 Voltage detection with two contact electrodes (bi-polar detectors) . 32
A.2.3 Voltage detection with one contact electrode . 33
A.2.4 Voltage detection without contact electrode . 34
Annex B (informative) Instructions for use . 36
Annex C (informative) In-service care . 37
C.1 General . 37
C.2 Maintenance . 37
Annex D (informative) Suitable for live working; double triangle . 38
Bibliography . 39
Figure 1 – NCVD working at a distance without any contact . 12
Figure 2 – Effect of the relative position of the non-contact voltage detector . 13
Figure 3 – NCVD working at a distance with one reference point . 14
Figure 4 – Non-contact voltage detector with a reference point making contact with the
cable insulation covering an insulated conductor . 15
Figure 5 – Non-contact voltage detector working with two reference points making
contact with the cap and pin of an insulator . 16
Figure 6 – Non-contact voltage detector working with two reference points on an
underground cable . 16
Figure 7 – Directional properties of NCVD working at distance. 25
Figure 8 – Examples of designs of NCVDs . 29
Figure A.1 – Bi-polar voltage detection principle . 33
Figure A.2 – Capacitive unipolar voltage detection principle . 34
Table 1 – Types of non-contact voltage detector . 18
Table 2 – Limitations for use . 19
Table 3 – Specific recommendations for use . 20
Table 4 – Examples of values of the radius of the cone of detection as a function of
the directional properties angle . 24
Table 5 – Climatic categories . 26
Table 6 – Minimum length of the insulating element or of the insulating stick (L ) . 30
i
Table C.1 – Recommended checking points for in-service care . 37
– 4 – IEC TR 61243-6:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LIVE WORKING – VOLTAGE DETECTORS –
Part 6: Guidelines on non-contact voltage detectors (NCVD)
for use at nominal voltages above 1 kV AC
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a Technical Report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 61243-6, which is a Technical Report, has been prepared by IEC technical
committee 78: Live working.
The text of this Technical Report is based on the following documents:
Enquiry draft Report on voting
78/1143/DTR 78/1162A/RVDTR
Full information on the voting for the approval of this Technical Report can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
Terms defined in Clause 3 are given in italic print throughout this standard.
A list of all parts of the IEC 61243 series, published under the general title Live working –
Voltage detectors, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – IEC TR 61243-6:2017 © IEC 2017
INTRODUCTION
With the aim of ensuring the safety of the users the purpose of a voltage detector is to give a
clear indication of the presence or absence of the operating voltage, without any need for
interpretation or analytical evaluation by the user.
IEC 61243-1, IEC 61243-2 and IEC 61243-3 apply to portable voltage detectors designed to
work correctly when they are in direct contact with the bare part of the installation to be
tested.
At HV and UHV, large distances between the user and the bare parts to be tested make the
handling of a very long insulating element or insulating stick an ergonomic and safety
concern. In such situations, it may become convenient to avoid any contact with the bare part
to be tested and to perform voltage detection at a distance.
This document provides considerations and performance guidelines for portable “non-contact”
voltage detectors and it can be used as a reference for the development of national, industry
or manufacturer's standard(s) or for the selection of a product by users.
This document has been prepared taking into consideration the provisions given in
IEC 61477.
LIVE WORKING – VOLTAGE DETECTORS –
Part 6: Guidelines on non-contact voltage detectors (NCVD)
for use at nominal voltages above 1 kV AC
1 Scope
This part of IEC 61243, which is a Technical Report, is applicable to portable non-contact
voltage detectors (NCVD) with built-in power source, to be used to indicate the presence or
the absence of the operating voltage on electrical systems for nominal voltages above 1 kV
AC and frequencies of 16 2/3 Hz, 50 Hz and/or 60 Hz.
NOTE 16,7 Hz is often referenced.
This document applies only to devices that are not designed to be used in contact with the
bare part of the installation on which the presence or the absence of the operating voltage
has to be tested.
This document describes only devices, and their behaviour, using electric field and voltage
gradient detection principles even if other principles could be used. It provides performance
guidelines, recommendations for use and recommended minimum criteria for selection.
Devices like personal safety distance voltage detectors, distance voltage detectors for
emergency responders or machine operators are not covered by this document.
Except when otherwise specified, all the voltages defined in this document refer to phase-to-
phase voltages of three-phase systems. In other systems, the applicable phase-to-phase or
phase-to-earth (ground) voltages are used to determine the operating voltage.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 61318, Live working – Conformity assessment applicable to tools, devices and equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61318 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
adaptor
part of an NCVD as a separate device which permits attachment of an insulating stick
– 8 – IEC TR 61243-6:2017 © IEC 2017
3.2
application mark
mark on the NCVD to show to the user where to put the NCVD at the application point for
clear indication
Note 1 to entry: An application mark may or may not be present.
3.3
application point
specific point of the installation where the application mark (if present) of the NCVD should
correspond
Note 1 to entry: An application point may or may not be needed.
3.4
active signal
audible or visual phenomenon whose presence, absence or variation is considered as
representing information on the condition “voltage present” or “voltage not present”
Note 1 to entry: A signal indicating only that the NCVD is ready to operate is not considered as an active signal.
3.5
clear indication
unambiguous detection and indication of the voltage state of the part to be tested
3.6
clear perceptibility
case where the indication is unmistakably discernible by the user under specific
environmental conditions when the NCVD is in its operating position
3.7
contact electrode
bare conductive part of a voltage detector which establishes the electric connection to the
component to be tested
3.8
design of NCVD
different constructions of NCVDs, either as a complete device with or without an insulating
element or as a separate device intended to be equipped with an insulating stick
3.9
directional property
property whereby an NCVD detects an electrical field relative to a specific position
3.10
electrode
metallic part of an NCVD combined with one or more other metallic parts that allows to pick
up the electric field
3.11
expected voltage
maximum voltage value of the part of the installation that will or could be touched by the
NCVD
3.12
far electric field
far field
in free space, region where the distribution of the electrical field is almost independent of the
distance to the source
3.13
hand guard
distinctive physical guard separating the handle of an NCVD as a complete device from the
insulating element
Note 1 to entry: The purpose of the hand guard is to prevent the hands from slipping and passing into contact
with the insulating element.
3.14
indicator
part of the NCVD that indicates the presence or absence of the operating voltage for the part
of the electrical equipment or installation to be tested
3.15
indoor type
NCVD designed for use in dry conditions, normally indoors
3.16
insertion depth
distance between the limit mark and the top of the NCVD as a complete device
3.17
insulating element
part of an NCVD as a complete device that provides adequate safety distance and insulation
to the user
3.18
insulating stick
insulating tool made essentially of an insulating tube and/or rod with end fittings
Note 1 to entry: For voltage detection, an insulating stick is intended to be attached to the NCVD as a separate
device in order to provide the length to reach the installation to be tested and adequate safety distance and
insulation to the user.
[SOURCE: IEC 60050-651:2014, 651-22-01, modified – Note 1 to entry has been added.]
3.19
interference field
electric field due to the configuration of the installation that may
affect the electric field of the part to be tested
3.20
interference voltage
voltage picked up inductively or capacitively by the part to be tested
3.21
limit mark
distinctive visible location or mark on the NCVD to indicate to the user the physical limit to
which the NCVD could be inserted between live parts
Note 1 to entry: A limit mark may or may not be present.
3.22
medium electric field
medium field
in free space, region where the distribution of the electric field is slightly dependent on the
distance to the source
– 10 – IEC TR 61243-6:2017 © IEC 2017
3.23
near electric field
near field
in free space, region where the distribution of the electrical field is strongly dependent on the
distance to the source
3.24
nominal distance
D
n
suitable value of distance, between the bare part of the installation to be tested and the
NCVD, associated with the nominal voltage of the NCVD for clear indication
Note 1 to entry: The nominal distance of the NCVD is a parameter associated with its clear indication. The
manufacturer can identify the nominal distance directly linked to the corresponding discrete nominal voltage.
Note 2 to entry: An NCVD may have more than one nominal distance when having more than one nominal
voltage, or one or more than one nominal voltage range. In this case, for each nominal voltage or each nominal
voltage range the manufacturer can identify at least one characteristic discrete nominal voltage. The manufacturer
can then identify the nominal distance directly linked to each corresponding discrete nominal voltage.
Note 3 to entry: For some devices, the nominal distance(s) could be defined by the NCVD reference points.
3.25
nominal voltage
U
n
suitable approximate value of voltage used to identify a system or device
Note 1 to entry: The nominal voltage of the NCVD is a parameter associated with its clear indication. An NCVD
may have more than one nominal voltage, or a nominal voltage range. Limit values of the nominal voltage range
are named U and U
n min n max
[SOURCE: IEC 60050-601:1985, 601-01-21, modified – The definition has been modified to fit
the specific context of device or equipment and Note 1 to entry has been added.]
3.26
non-contact voltage detector
NCVD
voltage detector that does not require making physical contact with the bare part of the
installation (e.g. conductor, bus bar, capacitive tap for a cable elbow or switchgear) on which
the presence or the absence of the operating voltage has to be tested
3.27
operating distance range
range of distances to the bare part to be tested declared by the manufacturer where the
NCVD will function properly when used according to the instructions for use
Note 1 to entry: For some devices, the operating distance could be defined by the NCVD reference points.
3.28
outdoor type
NCVD designed for use in wet conditions, either indoors or outdoors
3.29
operating voltage
system voltage under normal conditions at a given instant and location
Note 1 to entry: This value may be calculated or measured.
3.30
protection against bridging
protection against flashover or breakdown, when the insulation between the parts of the
installation to be tested, at different potentials, is reduced by the presence of the NCVD
3.31
rated voltage
U
r
value of voltage to which certain operating specifications are referred
Note 1 to entry: The rated voltage of the NCVD is the voltage selected from IEC 60071-1:2006+AMD1:2010,
Table 2 and Table 3, column 1, which should either be equal to the nominal voltage (or the highest nominal voltage
of its nominal voltage range), or the next higher voltage selected from those tables.
3.32
reference point
point of an installation which is different from the bare part to be tested and which needs to be
touched in order to give an electrical reference according to the principle of functioning of
some NCVD
3.33
response time
time delay between sudden change of the voltage state on the part to be tested and the
associated clear indication
3.34
testing element
built-in element or separate device by means of which the functioning of the NCVD can be
checked by the user
[SOURCE: IEC 60743:2013, 11.3.7, modified – The definition has been modified to apply
specifically to NCVD.]
3.35
threshold voltage
U
t
minimum voltage between the live part and earth (ground) required to give a clear indication
corresponding to specific conditions as defined in the corresponding test
Note 1 to entry: As defined in this part of IEC 61243, threshold voltage is related to specific test conditions. Users
should be aware that their requirements for threshold voltage for field operation need to be related to the test
conditions.
3.36
voltage detector
diagnostic device used to provide clear evidence of the presence or absence of an operating
voltage
Note 1 to entry: These diagnostic devices are generally described as either capacitive type or resistive type.
Note 2 to entry: Clear evidence is a YES or NO indication with no interpretation needed. Sometimes, voltage
detectors also have supplementary function(s) such as the display of voltage values.
[SOURCE: IEC 60050-651:2014, 651-24-02]
4 The principles of an NCVD
4.1 NCVD designed to work at a distance without any contact
A non-contact voltage detector working at a distance operates by detecting the AC electric
field generated in free air by the energized part of the installation to be tested. This detection
is typically carried out via the use of a minimum of two internal metallic electrodes positioned
at some distance apart. It is possible to represent the electric configuration as being
equivalent to two stray capacitances. One is measured between the part to be tested and the
first (internal) electrode of the voltage detector. The other is measured between the second
(internal) electrode and the surrounding space (including earth) as shown in Figure 1. It
– 12 – IEC TR 61243-6:2017 © IEC 2017
should be noted that the closer an NCVD approaches the part to be tested, the more similar it
becomes to a unipolar capacitive type (see Annex A).
IEC
Key
1 part to be tested
2 earth
3 non-contact voltage detector with its two internal electrodes
4 potential difference between the two electrodes of the voltage detector
5 electric field equipotential lines
Figure 1 – NCVD working at a distance without any contact
For this design of detector, the voltage detection is mainly based on the evaluation of an
electric field associated with a potential difference between the two floating electrodes. As the
electric potential at the floating electrodes is a function of the electric field distribution, the
distribution of the electric field will consequently affect the detection. In most of the
installation configurations, the electric field around a line or piece of equipment is not uniform.
The electrical field strength and the gradient of field are normally higher near the live part and
the strength and the gradient of field decreases as the distance from the live part increases.
The relative positioning of the NCVD with respect to the part to be tested is then a parameter
that may affect the correct indication of this type of NCVD. As illustrated in Figure 2, the
voltage difference developed between its two floating electrodes will depend on the gradient
of the electric field at and near the location of the NCVD. When the voltage detector is close
to the part to be tested (Position P1 of Figure 2a), the electric field changes rapidly with the
distance and a voltage difference will be easily detectable between the two floating
electrodes. Alternatively, if the voltage detector is too far from the part to be tested
(Position P2 of Figure 2a), the electric field will change only slightly with distance and the
voltage difference across the two electrodes could be too small for a correct detection.
If the position of the voltage detector is such that the electric field is practically independent of
location (i.e. nearly constant) at the position of the voltage detector (Position P3 of Figure 2b),
no significant voltage difference will be developed between the two floating electrodes. This
may result in an incorrect indication of the voltage detector (e.g. absence of voltage instead of
voltage present).
The shape of the part to be tested and the distance between this part and adjacent parts at
different potential will also affect the electric field distribution which consequently may affect
the indication of the device. The strength of the electric field at the surface of an energized
part will decrease with the height of that part above earth, and will also decrease as the size
of the part increases. Also, adjacent parts at the same potential as the energized part will
generally reduce the strength of the electric field distribution locally (in-phase interference
field). Conversely, an adjacent part at the earth potential will increase the strength of the
electric field distribution near the energized part (out-of-phase interference field). Finally, live
parts in the vicinity of a de-energized part to be tested may create locally electric field that
could affect the correct indication of the device. In this case the indication "voltage present"
can appear although the part is de-energized.
IEC
IEC
Figure 2a – Effect of the distance Figure 2b – Effect of the position relative
to the part to be tested to the equipotential lines
Key
1 part to be tested
2 earth
3 non-contact voltage detector with its two internal electrodes
V potential difference between the two internal electrodes of the voltage detector
5 electric field equipotential lines
P1 position of the voltage detector close to the part to be tested
P2 position of the voltage detector far from the part to be tested
P3 position of the voltage detector where no equipotential lines are crossed
Figure 2 – Effect of the relative position of the non-contact voltage detector
As stated previously, application of the NCVD is a very important consideration in order to
obtain a reliable detection.
Like capacitive voltage detectors (IEC 61243-1), NCVDs may be affected by electrostatic
discharges, especially in cases of low voltage and/or far field applications where high
sensitivity is required. Electrostatic charges are typically generated by mechanical friction.
This friction causes displacement of electrons in insulating materials and accumulation of
charges. As static charges do not vary over time, AC voltage detectors should not be affected.
However, in case of discharges of the static charges the frequency spectrum of these
discharges contain signals that vary over a certain time for a short period and may cause
random triggering of the detecting circuit.
4.2 NCVD designed to work with reference points
4.2.1 General
Another category of non-contact voltage detectors consists of those that require an electrical
reference by contacting one or two parts of the installation other than the bare part to be
tested.
– 14 – IEC TR 61243-6:2017 © IEC 2017
4.2.2 NCVD designed to work with one reference point
The functioning of devices with one reference point is generally based on capacitive coupling
or electric field detection. In some cases the reference point is connected to earth (for
example, enclosed switchgear), while in other cases the reference point is in contact with the
cable insulation covering of an insulated conductor.
When the reference point is the electric earth, the functioning is based on the evaluation of
the potential difference (electric field) between the reference point and the floating electrode
(see Figure 3).
IEC
IEC
Figure 3a – NCVD with one reference Figure 3b – NCVD used on metal
point at the electric earth enclosed equipment
Key
1 part to be tested
2 earth
3 floating electrode of the voltage detector
4 reference point of the voltage detector (electric earth)
5 electric field equipotential lines
V potential difference between the floating electrode and the electric earth
Figure 3 – NCVD working at a distance with one reference point
When the reference point is the cable insulation covering of an insulated conductor, the
functioning is based on capacitive coupling between the contact electrode of the voltage
detector and the conductor, and the stray capacitance between the floating electrode of the
voltage detector and earth (see Figure 4).
IEC
Key
1 non-contact voltage detector 5 contact electrode of the voltage detector
2 insulating covering 6 floating electrode of the voltage detector
3 part to be tested (conductor) 7 stray capacitance between the floating electrode of
the voltage detector and earth
4 capacitive coupling between the contact electrode 8 earth
of the voltage detector and the conductor
Figure 4 – Non-contact voltage detector with a reference point making contact
with the cable insulation covering an insulated conductor
4.2.3 NCVD designed to work with two reference points
Devices with two reference points rely on the detection of a potential difference.
The first example refers to a device designed to be used on a single insulator of an insulator
string where the two reference points are respectively the cap and the pin of an insulator. The
insulator string is considered to be a series of capacitors connected between the live part and
earth. The last few insulators at the earth side of the insulator string may be considered as
the low side of a voltage divider. The voltage detector operates by detecting the voltage
across the cap and pin of one insulator closest to the earthed side of an insulator string, see
Figure 5.
The second example refers to a device designed to be used on certain types of underground
cable. It operates by detecting the voltage across the semi-conductive layer and the
concentric neutral of the cable (Figure 6). When the cable is energized, a displacement of
electrons in the insulating materials creates an accumulation of charges at the interface of the
insulating material and the semi-conductive layer. This generates a voltage polarization
between the semi-conductive layer and the concentric neutral of the cable.
– 16 – IEC TR 61243-6:2017 © IEC 2017
IEC
IEC
Figure 5a – NCVD used on a unit of an Figure 5b – Equivalent electrical circuit of an
insulator string insulator string
Key
1 non-contact voltage detector
2 contact electrodes
3 part to be tested (conductor)
4 earth
V voltage across the cap and pin of one insulator (capacitance) on the earthed side of the insulator string
Figure 5 – Non-contact voltage detector working with two reference points
making contact with the cap and pin of an insulator
IEC
Key
1 concentric neutral
2 semi-conductive layer
3 neutral wire
V voltage between the semi-conductive layer and the concentric neutral
Figure 6 – Non-contact voltage detector working with
two reference points on an underground cable
5 Different designs of non-contact voltage detectors
The various types of NCVD are presented in Table 1. NCVDs are classified in five types
according to their design.
Types 1, 2 and 3 are NCVD working at a distance (without any contact). These are the most
commonly used types worldwide.
A Type 1 NCVD (T1a in Table 1) is designed to be used far from the live working zone and
therefore is not considered as a "live working device". As such it does not fall under the scope
of IEC TC 78. Therefore, this document does not recommend indications or/and requirements
for this type of NCVD. However, Type 1 could be used from the ground (T1b in Table 1) or a
tower as a “pre-diagnostic” device whose indication should be later confirmed by another type
of voltage detector with more reliability.
A Type 2 NCVD (T2a in Table 1) is designed to be used from a tower near an insulator string
or from the ground near an insulator column or from any identifiable location and may
penetrate the live working zone. This type of NCVD falls within the scope of IEC TC 78. T2b in
Table 1 shows an example of the device in use from a tower.
A Type 3 NCVD (T3a in Table 1) is designed to be used inside the live working zone with an
adaptable insulating stick (T3b in Table 1). This type of NCVD falls within the scope of
IEC TC 78.
Types 4 and 5 are NCVDs with at least one reference point. They are designed for specific
applications.
Type 4a is designed for use on metal enclosed switchgear and penetrates the live working
zone (T4a in Table 1). This type of NCVD falls within the scope of IEC TC 78. Type 4b is only
designed to be used on insulated conductors (T4b in Table 1) and is never used within the
live working zone, therefore, it is not considered as a "live working device". As such it does
not fall under the scope of IEC TC 78. Therefore, this document does not recommend
indications or/and requirements for this type of NCVD.
Type 5a is designed to be used on cap and pin insulator string (T5a in Table 1). This type of
NCVD falls within the scope of IEC TC 78. Type 5b is only designed to be used on an
underground network and is never used within the live working zone (T5b in Table 1),
therefore, it is not considered as a "live working device". As such it does not fall under the
scope of IEC TC 78. Therefore, this document does not recommend indications or/and
requirements for this type of NCVD.
– 18 – IEC TR 61243-6:2017 © IEC 2017
Table 1 – Types of non-contact voltage detector
Type 1 Type 2 Type 3 Type 4 Type 5
Far electric field Medium electric field Near electric field One reference point Two reference points
Outside the LW zone (Mostly) outside the LW zone Inside the LW zone
Designed for use from ground or Designed for use near an Designed for use near the bare Designed for use on metal Designed for use on cap and pin
from the tower insulator string or insulator part to be tested enclosed switchgear or covered insulator string or on certain
column conductor design of underground power
cable
Without any reference point With one or more reference points
IEC IEC
IEC IEC IEC
T1a – example of type 1 T2a – example of type 2 T3a – example of type 3 T4a – Type 4a for switchgear T5a – Type 5a for insulator
application string for aerial transmiss
...
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