TITLE: POWER [TERMINAL FOR HIGH CURRENT AND HIGH
TEMPERATURE APPLICATIONS
FIELD OF IN VENTION
The invention relates to developing electrical terminal in general and to power
terminal for high current and high temperature application, in a hostile
environment of high temperature with natural cooling in particular.
BACKGROUND OF INVENTION AND PRIOR ART
A test facility for developing the technology for supercritical boilers involves the
simulation of boiler evaporators to study the thermodynamic/ heat transfer
characteristic of super critical fluid at a pressure of 400 bar and a temperature of
700 Deg C. The required fluid temperature of 700 deg C is brought in stages
through a set of electrical furnaces and finally through joule heating through the
evaporator tube. Joule heating/Resistive heating is preferred in the final stages
of heating in order to have fine control over the heat input in to the system so
that thermodynamic behaviour of super critical fluid can be studied precisely.
The joule heating on the boiler tube is done by way of passing very high current
of about 5000 Amps DC through the metal portion of the tube. Since the
supercritical fluid will already be around the temperature of 400 Deg C when
entering in to the evaporator, as it comes through the stages of electrical
furnaces, it will be difficult to transfer the power using the cables and

termination generally available in the market because it will burn the cables due
to excess temperature of evaporator tube. Otherwise an external low
conductivity water- cooling arrangement is to be employed to cool the
terminations and cables. But this will also take away the heat unnecessarily from
the evaporator, which is undesirable because again more power is to be put into
the system to offset the effect due to cooling.
Hence a suitable device is required to put the power in to the evaporator, which
will not take away the heat from the evaporator and at the same time the power
carrying cable and terminations are protected.
OBJECT OF INVENTION
To overcome to drawbacks of the prior art the following objection are considered
to adapt remedial innovative measures.
(a) To propose a device, which carries a very high current to a load, which
is already at high temperatures.
(b) To propose a device, which carries a very high current to load, which
is already at high temperatures without any external cooling
arrangement.
(c) To propose a device, which is less expensive, for carrying a very high
current to a load that is already at high temperatures.

DESCRIPTION OF INVENTION
A less expensive, air-cooled power terminal to carry very high current to a load
at very high temperature considering the electrical, thermal and mechanical
characteristics of the material of power terminal and various aspects of service
environment.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Fig 1 shows the Power Terminals.
Fig 2 shows the setup where the terminals are mounted.
The invention will now be described with accompanying drawings which depict
an exemplary embodiedment of invention. However, there can be other
embodiments, all of which are deemed covered by the description.
Power Terminal is a two semicircular configuration when connected to the
pipeline will form the wheel shaped structure (11). The two semicircular
structures (7) will be fastened through the bolts so that it is secured well on the
evaporator tube. Two sets of semicircular power terminals (fig 1) are connected
on either side of the hot tube (9) e.g. (evaporator tube/Boiler tube) when the
hot fluid would pass through. The inner ring (3) of the wheel is connected to the
outer ring (4) through spokes (2). There are two plates fixed (1) on

circumferencial outer ring (4) of the power terminal for connecting the power
cables (10) from the power supply (6). The figure also indicates the how the
power source (6) is connected to the load, i.e. hot tube (9). The flanges (8)
shown in the drawing are electrically insulated.
The proposed device is to increase the heat transfer area so that heat conducted
from the hot tube (9), say of the evaporator (9) will be dissipated to the
surrounding environment. The optimum number of spokes (2) of the device is
arrived to increase the number parallel paths for the current transfer. The
number of parallel paths (2) minimizes the electrical power loss in the terminals
i.e the no of spokes (2) of wheel is arrived for increasing the heat transfer area
and to increase the current carrying capacity. The length of the spokes (2) is
decided based on the requirement that the temperature at the circumferencial
outer ring (4) is less than 100 Deg C so that it doest not heat up the cables (10)
that bring power to this terminal. The diameter (2) of power terminal is fixed to
minimize the voltage drop across the terminal.
The material for construction of power terminal is selected as stainless steel after
due consideration of electrical and cost factors of copper and stainless steel.
Stainless steel prevents high temperature corrosion and facilitates easy
fabrication.
The height (5) and thickness of each and spoke (2) decides the current transfer
area for each spoke (2).

The height is arrived at considering the resistivily of Stainless Steel and the
current to be transferred, minimum voltage drop, minimum ohmic loss between
the outer ring (4) and the inner ring (3).
Detailed Thermal analysis (Through CFD Software) is done for various diameter
of the wheel, varying the no of spokes (2) and assuming different levels of ohmic
losses etc. The above exercise was also carried out for assuming different heat
transfer coefficients and finally arrived at design as shown in Fig 1.

WE CLAIM
1. Power terminal for high current and high temperature application
comprising :-
a plurality of semicircular structure of electrical conductor, having
arrangement of fastening through bolts on either side of the hot
tube (9), thereby forming power terminals(ll) in the form of a
wheel; the inner ring (3) of the wheel being connected to the
outer ring (4) where a plurality of connecting plates (1) are fixed
for connecting power cables (10) from the power supply (6);
through a plurality of spokes (2) to increase the surface area of the
terminal and the parallel path of current,
Characterized in that said power terminal, inspite of carrying very
high current to a load at very high temperature is naturally cooled
and maintain the temperature of less than 100 Deg C at the outer
ring (4) to avoid heating up the cables (10).
2. Power terminal as claimed in claim 1 wherein each semicircular
electrical conductors (7) comprise of at least two sets, each set
being connected on either side of said hot tube (9).
3. Power terminal as claimed in claim 1 wherein each electrical
conductor is made of stainless steel.

4. Power terminal as claimed in claim 1 wherein each semicircular
structure (7) has two connecting plates (1).
5. Power terminal as claimed in claim 1 wherein the height (5) and
thickness of each spoke (2) decide the current transfer area for
each spoke.

Power terminal for high current and high temperature application comprising:-
a plurality of semicircular structure of electrical conductor, having arrangement
of fastening through bolts on either side of the hot tube (9), thereby forming power terminals(11) in the form of a wheel; the inner ring (3) of the wheel being connected to the outer ring (4) where a plurality of connecting plates (1)
are fixed for connecting power cables (10) from the power supply (6); through a plurality of spokes (2) to increase the surface area of the terminal and the parallel path of current,
Characterized in that said power terminal, inspite of carrying very high current to
a load at very high temperature is naturally cooled and maintain the temperature of less than 100 Deg C at the outer ring (4) to avoid heating up the cables (10).