Cable End Termination Systems Type CETS, 100 kV

Cable End Termination Systems
Type CETS, 100 kV up to 800 kV
Situation & Application
HV tests of extruded cables require special measures for
the connection of the HV source to the cable under test. Watercontrolled cable end termination systems allow a reliable and
easy handle of this connection. The required international
standards and requirements for testing cables are all fulfilled by
using our cable end termination systems (IEC 60840 / 30-150kV,
IEC 62067 / 150-550kV, IEC 60060-1, IEC 60060-2, IEC 60270).
Cable End Termination Systems (CETS) are designed and
manufactured for routine and type testing of medium, high
and extra high voltage plastic-insulated cables. Additionally,
the system can also be operated in the framework of
development tests and other applications as:
HV AC withstand tests
PD measurement tests (the terminations are PD free up
to the rated voltage of the system)
HV impulse (LI and SI) tests
Step-up tests
HV AC long term tests (the system is designed for
continuous duty cycle)
C/tan δ measurement on request (special preparation of
the cable ends without changing of water end
Notice, CETS are not intended for cable operation or service after
installation. In addition, if high current tests above 100 A are
needed, this has to be considered from case to case.
Cable Terminations
The general principle is based on the field-control by using
deionised water with a specific, controllable conductivity together
with its high dielectric constant. As cable diameters can vary the
electric field distribution can change significantly within the same
cable end termination. Thus a suitable field-control is needed,
that means the correct conductivity within the cable termination is
crucial and thus an important design factor of the cable end
terminations. Furthermore, one negative consequence of using
water with limited conductivity as a medium for the correct fieldcontrol, electric energy is dissipated within the water. This may
lead to a significant and unwanted temperature rise. This effect is
avoided by the application of an effective cooling system for the
water and by choosing the correct conductivity.
The main components of the cable end termination system
consist of two cable end terminations CET for each end of the
cable to be tested and the water conditioning unit, CEU, see title
figure. Additionally, accessories like silicone sealing compound,
deionisation resin, water tubes and spare parts complete this
testing system. The cable is inserted from below into the end
termination for voltages up to 800 kV, Fig. 1.
The termination CET is designed as a 2-tube system in
which the deionised water circulates. Together with the water
conditioning unit a closed water system is formed. Each cable
termination is connected by two hoses to the water conditioning
unit, see title figure.
The CETS series includes terminations from 100 kV up to
800 kV for a maximum cable diameter of 160 mm over the outer
semi-conducting layer. Cable end terminations are based on the
field control within the end termination and in the ambient air by
using water with a specific and adjustable conductivity. Due to the
concept of the fully automatic control of the conductivity, the
temperature as well as the filling and emptying process, the cable
end termination systems are perfectly suited to perform all above
mentioned tests. They were developed in such a way that they
can be delivered as fully automatic stand-alone systems. The
great advantage for the user is a comfortable and easy
integration into the existing control and measuring system of the
HV test equipment via a fibre optic link.
Fig. 2: CET 300/120 with manual
jacking system
Fig. 3: CET 300/120 with
motorized jacking system
To lift the CET a standard version with manual jacking system,
Fig. 2, is available. The motorized version, Fig. 3, is offered as an
Fig. 1: View of a cable end termination for 300 kV, CET 300/120
Water Processing Unit
Two water processing units, type CEU are available to
cover all needs for the voltage levels from 100 kV up to 800 kV.
Design and geometry of the cables to be tested change the field
distribution and energy losses within the cable end termination.
The water conditioning unit is the key component which controls
both conductivity and temperature of the water circulating through
the cable end terminations.
The water conditioning unit (Fig. 4) is equipped with a
sufficient water reservoir which holds the deionised water.
Together with the two cable terminations, which are connected by
four hoses with the water conditioning unit, a closed water system
is formed, see title figure. By an effective pump, the water is
circulated with a flow rate of 30 l/min. or 60 l/min. through the
cable end terminations. With the help of a heat exchanger the
excess heat is taken away by external cooling water. The
conductivity is controlled by a deionisation resin contained in a
bottle. The arrangement of this bottle within the water circulating
system in conjunction with the conductivity control allows a very
long life time of about one year, even if the system is used
Control of water condition:
The four different operation states
Deionisation / Internal circulation
Charging / External Circulation
Testing / External Circulation
can easily be selected by buttons on the touch panel (Fig. 5).
All operation states, critical values like conductivity, temperature,
and water flow rate can be preset and are automatically
processed and controlled. No manual operations are necessary
like opening and closing valves or a manual correction of the
conductivity during a HV test. If critical conditions occur, as water
leaks or overheating, a signal is produced and the high-voltage
will be automatically switched off. Fig. 6 shows as an example the
visualization of the key parameters during cable testing on the
CEU touch screen.
Easily changeable bottle with
deionization resin
Control cabinet with touch panel
Cabinet for water processing,
measurements etc.
Hose connections for two CETs
Hose connection for
external cooling water
Fig. 4: Front view of CEU 120
Via a fibre optic link and by the PROFIBUS system, the
water conditioning unit can be incorporated in the HIGHVOLT
control and measurement system of high voltage AC and LI
This allows visualization on a central display, the remote control
of all parameters and the starting of all processes of the CEU.
Furthermore, for very high voltage applications and power, two
CEUs can be controlled by only one touch panel, as the two
water conditioning units can be connected by one optical fibre
As heat losses rise strongly with the increase of the applied
voltage level and by decrease of the cable diameter (volume of
water is increased), cooling capacities for the CEUs cover two
ranges. The smallest CEU has a maximum cooling capacity of
60 kW and the larger version is equipped with a cooling capacity
of 120 kW.
Fig. 5: Visualization of key parameters on the CEU touch
screen during testing
Available Systems
Type designation for the cable end termination systems and
their components is as follows:
The cable terminations alone:
CET a/b G
rated voltage
maximum cable diameter in mm across
semi-conducting layer
guard electrode for tan δ measurement
(as option)
The system (consisting of two cable end terminations together
with the water conditioning unit):
CETS a/b-c
rated voltage in kV
maximum cable diameter in mm across
semi-conducting layer
maximum cooling capacity in kW
Example: CET 350/120 is a pair of cable end termination for
350 kV, 120 mm across semi-conducting layer
Example: CETS 350/120-60 is a system for 350 kV, 120 mm
across semi-conducting layer, 60 kW cooling capacity
The water conditioning unit:
Further technical information about the components can be found
in the HIGHVOLT Data Sheets No. 7.93 and 7.95
maximum cooling capacity
remote control (as option)
Example: CEU 120 means a water conditioning unit with 120 kW
cooling capacity
Pair of cable terminations
Water Conditioning Unit
Accessories 2)
CETS 100/120-60
CET 100/120
CEU 60
CEA 100/120
CETS 150/120-60
CET 150/120
CEU 60
CEA 150/120
CETS 200/120-60
CET 200/120
CEU 60
CEA 200/120
CETS 250/120-60
CET 250/120
CEU 60
CEA 250/120
CETS 300/120-60
CET 300/120
CEU 60
CEA 300/120
CETS 350/120-60
CET 350/120
CEU 60
CEA 350/120
CETS 350/160-60
CET 350/160
CEU 60
CEA 350/160
CETS 400/120-60
CET 400/120
CEU 60
CEA 400/120
CETS 400/160-120
CET 400/160
CEU 120
CEA 400/160
CETS 500/120-120
CET 500/120
CEU 120
CEA 500/120
CETS 500/160-120
CET 500/160
CEU 120
CEA 500/160
CETS 600/120-120
CET 600/120
CEU 120 1)
CEA 600/120
CETS 600/160-120
CET 600/160
CEU 120
CEA 600/160
CETS 700/120-240
CET 700/120
2 x CEU 120
CEA 700/120
CETS 700/160-240
CET 700/160
2 x CEU 120
CEA 700/160
CETS 800/160-240
CET 800/160
2 x CEU 120
CEA 800/160
Detailed technical data
see data sheet 7.93
see data sheet 7.95
Table 1: Overview of cable end termination system CETS
For further information please contact:
or our local representative:
optional are also two CEU 120, each for one cable end termination
) includes spare parts, silicone sealing compound, deionization resin
HIGHVOLT Prüftechnik Dresden GmbH
Marie-Curie-Straße 10
D-01139 Dresden / Germany
Telephone: ++49 351 84 25-648
++49 351 84 25-679
web site:
© HIGHVOLT Prüftechnik Dresden GmbH - 2013/09- 7-90-3.doc Subject to change without prior notice
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