The ELEKTRO
1/2012
Customer information for electro-technical specialists
Collection of new ideas in the Electrotechnical Industry
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 development, manufacture and application of
such products. At the same time we
have been contributing for many decades to the formulation of the relevant
standards and regulations.
With the further spread of PV installations and DC generation, the question
of protection against electric shock
98 17 0654 02.10/101/12
now requires a totally new approach:
with the correct installation of our totally insulated products, we guarantee
the absolute safety of the generator junction boxes installed. – So you
know you are safe!
Sincerely
Felix G. Hensel
Managing partner of
Gustav Hensel GmbH & Co. KG
Array junction boxes 
must be total insulated!
A strong requirement of the IEC standard for
protection against electric shock in PV plants.
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 protect against electrical shock.
How is the protection against electric shock guaranteed
in photovoltaic systems on the DC side?
How is the protection against electric shock guaranteed in
photovoltaic systems on the DC side?
up to DC 1000 V
PV-grid scheme DC-side
DC
AC
IEC 60 364-7-712
requires for the installation
of photovoltaic (PV) power
supply systems:
Equipment standard
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).
Protection measures
712.413.2
Protection by use of class II or
equivalent insulation should
preferably be adopted on the
DC side.
1
PV Generator
2
PV Array Junction Box (AJB)
3
Solar Inverter
Why does IEC 60 364-7-712 require protection class II ()
for PV array junction boxes?
In grounded systems a earth
fault short circuit current
flows through the protective device and leads to a
switch-off.
On the DC side of a PV installation, the maximum short circuit 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, because the residual current is too
low.
As a consequence the protection 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 enclosures (equipment of protection
class II) fulfil this requirement.
Total insulated array junction boxes (AJB) according to IEC 61 439-1
ensure the protection against electric shock!
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 .
IEC 61439-1 requirements, clause 8.4.3.4
for total insulation 
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.
1 T
he apparatus shall be completely enclosed in insulating
material which is equivalent of
double or reinforced insulation.
st
2nd The enclosure shall carry the
symbol  which shall be visible from the outside.

The enclosure is made of high
quality polycarbonate.
Specifications:
3rd The enclosure shall at no point
be pierced by conducting parts
in such a manner that there is
the possibility of a fault voltage being brought out of the
enclosure.
- Glow-wire test 960 ° C according to IEC 60 695-2-11,
self-extinguishing, flame
retardant
- UV-resistant according to
IEC 61439-1, Clause 10.2.4
4th The enclosure shall give at
least the degree of protection
IP 2XC (see IEC 60529).
- silikone- and halogenfree
- Resistant to weather-related
conditions such as rain, ice
and snow
5th The enclosure must be accessible 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.

Degree of protection IP 65
Testing of enclosures made of insulating material
in accordance with IEC 61439-1, 10.9.4
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
690-800 V DC
800-100 V DC
test voltage
4,245 V
4,665 V

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!
KV Small-type distribution
boards up to 63 A,
3 to 54 modules, IP 54- 65
Distribution boards
Combinable enclosure system
with door up to 250 A, IP 65
Mi Distribution boards
up to 630 A, IP 54-65
Cable entry systems
Construction board panels
up to 630 A, IP 44-65
Phone: +91-44-3727 0202
Fax: +91-44-3727 0200
Email: info@hensel-electric.in ∙ www.hensel.in
Installation of total insulated array junction boxes in photovoltaic
systems according to IEC standards:
DK Cable junction boxes
2
1.5 to 240 mm , IP 54-67
Sunguvachathram - Walajabad Road
4th km behind Samsung/Flextronics
Sriperumbudur - 631 604 ∙ Kanchipuram Dist, Tamil Nadu
Hensel array junction boxes are total
insulated  and ensure the protection
against electric shock!
POWER.
PASSION FOR
More detailed information on this theme
proceed to download at www.hensel.in!
Product information
ENYSUN - Safe product solutions for Photovoltaic
plants conforming to standards
Grid, on-grid and off-grid systems
NEW
Product information
as at: 10/2011
ns for Photovoltaic
Safe product solutio
to standards
plants conforming
Grid, on-grid and
off-grid systems
GmbH & Co. KG
Gustav HenselPower Distribution Systems
Industrial Electrical
Altenhundem
e6
Gustav-Hensel-Straß
t, Germany
D-57368 Lennestad
n boxes
PV Generator junctio
tors
Battery distribu
ors
Solar inverter collect
areas of the new
For all application
(Draft)
IEC 60 364-7-712
standard
P.O. Box 1461
t, Germany
D-57344 Lennestad
23/6 09-0
Phone: +49 (0)27
23/6 00 52
Fax: +49 (0)27
el-electric.de
E-Mail: info@hens
de
www.hensel-electric.
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.
1
R. Rajesh
Managing Director
Hensel Electric India
Pvt Ltd
info@hensel-electric.in
www.hensel.in
Hensel Electric India Pvt Ltd
Industrial Electric Power Distribution Systems
35 Kunnam Village
Photovoltaik distributors
that meet the standards