Elektro Tipp - Array junction boxes: A strong requirement of the IEC standard for protection against electric shock in PV plants. To know more details click here: http://hensel.in

1. Felix G. Hensel
Managing partner of
Gustav Hensel GmbH & Co. KG
Dear Reader,
It was more than 80 years ago that
my father founded the Gustav Hensel
GmbH in Germany.
This was the time when duroplastics
became available for the first time for
the production of electrical installation
products. That was a major factor in
the early days of the company.
The use of insulating material for
enclosures is the company’s basic
philosophy throughout its existence
– which is why Hensel also disposes
of unique know-how in the develop-
ment, manufacture and application of
such products. At the same time we
have been contributing for many dec-
ades to the formulation of the relevant
standards and regulations.
With the further spread of PV installa-
tions and DC generation, the question
of protection against electric shock
now requires a totally new approach:
with the correct installation of our to-
tally insulated products, we guarantee
the absolute safety of the genera-
tor junction boxes installed. – So you
know you are safe!
Sincerely
How is the protection against electric shock guaranteed
in photovoltaic systems on the DC side?
The ELEKTRO
Customer information for electro-technical specialists 1/2012
Grids in building installations are
generally grounded. That means,
in the event of an electric fault a
protective device interrupts the
supply in the circuit, for example
by MCB or MCCB.
The DC power grid from photovol-
taic systems (installation between
PV module and solar inverter)
is not grounded and therefore
requires special measures to pro-
tect against electrical shock.
98
17
0654
02.10/101/12
Collection
of
new
ideas
in
the
Electrotechnical
Industry
Array junction boxes 
must be total insulated!
A strong requirement of the IEC standard for
protection against electric shock in PV plants.

2. How is the protection against electric shock guaranteed in
photovoltaic systems on the DC side?
Total insulated array junction boxes (AJB) according to IEC 61 439-1
ensure the protection against electric shock!
up
to
DC
1000
V
DC
AC
712.413.2
Protection by use of class II or
equivalent insulation should
preferably be adopted on the
DC side.
Protection measures
712.511.1
... The PV array junction boxes,
PV generator junction boxes and
swtichgear assemblies shall be in
compliance with IEC 60 439-1
(Since 2010: IEC 61 439-1).
Equipment standard
IEC 60 364-7-712
requires for the installation
of photovoltaic (PV) power
supply systems:
In grounded systems a earth
fault short circuit current
flows through the protec-
tive device and leads to a
switch-off.
On the DC side of a PV instal-
lation, the maximum short cir-
cuit current is the same as the
maximum operating current. This
means that devices for protection
against electric shock, such
as MCB or fuses, don‘t trip, be-
cause the residual current is too
low.
As a consequence the protec-
tion against electric shock is
not guaranteed in the event of
an electrical fault.
Total insulated equipment 
ensure the protection against
electric shock by encapsulating a
possible electric fault by double
or reinforced insulation.
In general, total insulated enclo-
sures (equipment of protection
class II) fulfil this requirement.
Why does IEC 60 364-7-712 require protection class II ()
for PV array junction boxes?
1
2
3 Solar Inverter
PV Array Junction Box (AJB)
PV Generator
PV-grid scheme DC-side

3.  Total insulated Hensel array junction
boxes (AJB) according to IEC 61 439 Part 1
ensure the protection against electric shock!
This standard specifies requirements and tests that will be placed on
an array junction box (AJB), particulary with respect to the required
total insulation .
1st
The apparatus shall be com-
pletely enclosed in insulating
material which is equivalent of
double or reinforced insulation.
3rd
The enclosure shall at no point
be pierced by conducting parts
in such a manner that there is
the possibility of a fault volt-
age being brought out of the
enclosure.
4th
The enclosure shall give at
least the degree of protection
IP 2XC (see IEC 60529).
IEC 61439-1 requirements, clause 8.4.3.4
for total insulation 
For assemblies with enclosures
made of insulating material, an
additional dielectric test shall
be carried out.
The test voltage has the following
values​​, for example:
Max. PV operating
voltage
test voltage
690-800 V DC 4,245 V
800-100 V DC 4,665 V
Testing of enclosures made of insulating material
in accordance with IEC 61439-1, 10.9.4
Conclusion:

Hensel array junction boxes are
total insulated 
according to the requirements
of IEC 61 439-1 and tested
up to an operating voltage of
1000 V DC.

The enclosure is made of high
quality polycarbonate.
Specifications:
-
Glow-wire test 960 ° C ac-
cording to IEC 60 695-2-11,
self-extinguishing, flame
retardant
-
UV-resistant according to
IEC 61439-1, Clause 10.2.4
- silikone- and halogenfree
-
Resistant to weather-related
conditions such as rain, ice
and snow

Degree of protection IP 65

DIN rails or other fixing ele-
ments are located exclusively
in the interior of the enclosure.
Metal parts may not come
through the encapsulation.

No use of metal cable entries.

Opening and closing per-
formed exclusively with tools!
5th
The enclosure must be acces-
sible only via the use of tools in
order to ensure the protection
against unintentional contact
of accessible live parts and the
exposed conductive parts that
are only accessible after the
cover has been opened.
2nd
The enclosure shall carry the
symbol  which shall be vis-
ible from the outside.

4. Installation of total insulated array junction boxes in photovoltaic
systems according to IEC standards:
Delivery in India via Hensel authorized distributor network
­
spanning 130 cities and industrial centers.
Delivery in South East Asia via Hensel authorized distributor
­
network in all ASEAN countries.
Hensel array junction boxes are total
insulated  and ensure the protection
against electric shock!
Distribution boards
Combinable enclosure system
with door up to 250 A, IP 65
DK Cable junction boxes
1.5 to 240 mm
2
, IP 54-67
KV Small-type distribution
boards up to 63 A,
3 to 54 modules, IP 54- 65
Mi Distribution boards
up to 630 A, IP 54-65
Cable entry systems
Photovoltaik distributors
that meet the standards
Construction board panels
up to 630 A, IP 44-65
R. Rajesh
Managing Director
Hensel Electric India
Pvt Ltd
info@hensel-electric.in
www.hensel.in
Sunguvachathram
-
Walajabad
Road
4th
km
behind
Samsung/Flextronics
Sriperumbudur
-
631
604
∙
Kanchipuram
Dist,
Tamil
Nadu
Phone:
+91-44-3727
0202
Fax:
+91-44-3727
0200
Email:
info@hensel-electric.in
∙
www.hensel.in
Hensel
Electric
India
Pvt
Ltd
Industrial
Electric
Power
Distribution
Systems
35
Kunnam
Village
Product information
ENYSUN - Safe product solutions for Photovoltaic
plants conforming to standards
Grid, on-grid and off-grid systems
More detailed information on this theme
proceed to download at www.hensel.in!
1
NEW
PASSION FOR POWER.
PV Generator junction boxes
Battery distributors
Solar inverter collectors
For all application areas of the new standard
IEC 60 364-7-712 (Draft)
Safe product solutions for Photovoltaic
plants conforming to standards
Grid, on-grid and
off-grid systems
Product information as at: 10/2011
Gustav Hensel GmbH Co. KG
Industrial Electrical Power Distribution Systems
Altenhundem
Gustav-Hensel-Straße 6
D-57368 Lennestadt, Germany
P.O. Box 1461
D-57344 Lennestadt, Germany
Phone:+49 (0)2723/609-0
Fax: +49 (0)2723/60052
E-Mail: info@hensel-electric.de
www.hensel-electric.de