Improvements in Electric Switchboards.
Year: 1898

page_text: Date of Application, 12th Dec., 1898-Accepted, 27th May, 1899
COMPLETE SPECIFICATION.
Improvements in Electric Switchboards.
We, EDWARD WOODROWE COWAN, of Hart Hill, Woodville Road, Bowdon,
Cheshire, Civil Engineer, and ALFRED STILL, of Bow Green Farm, Bowdon,
Cheshire, Civil Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
-
Our invention has for its object to provide an electric switchboard and fittings
in connection therewith combining simplicity, compactness and economy of con-
struction with ready access to the fittings and safety and efficiency in operation.
We will describe our invention with reference to the accompanying drawings,
Figure 1 being a transverse section and Figure 2 a front elevation of part of a
switchboard and fittings in accordance with our invention.
R is one of a number of rails, which are bolted to, bedded in, or otherwise
secured to the wall of the building in which the switchboard is erected, they being
spaced generally about 40 inches apart. Each of these rails is made with a
vertical slot or vertical slots allowing of bolts being adjusted vertically therein.
These rails carry, by means of the said Bolts, supports S for bus-bars B, B1,
and B, and terminals T. We prefer to make the said supports with bases of
insulating and incombustible material such for example as porcelain. Other
terminals, supports, and the like can be fixed to the rails in the same manner if
required for any special purpose.
At the lower end of each rail is a projecting bracket which we prefer to cast
with the said rail. These brackets carry small girders G preferably made of
cast iron which bridge the spaces between adjacent rails, thus forming a con-
tinuous support for the panels of the switchboard.
To the lower edge of each of the panels, (which may be of slate, marble, or any
other suitable material, and either wide or narrow according to requirements),
we bolt or otherwise fix, hinged brackets H, having trunnions which rest in
V" shaped grooves in lugs cast solid with, or otherwise attached to, the
girders G.
<<
The panels are retained in position by means of set screws K which pass through
holes in the upper ends of the panels and screw into small angle brackets U on
the inner side of a slab or slabs secured to the tops of the rails R.
The object of the "V" shaped grooves is to allow of the swinging of each
panel on its lower edge, and also to allow of its being easily and quickly removed.
Obviously the lugs with the "V" shaped slots can be fixed to the lower edge of
the panel, and the trunnions be on the girder as an alternative plan.
The object of the arrangement for hinging the panels on their lower edge is to
provide easy means for inspection of the back of the panel and to provide easy
access to the nuts, bus bars, terminals and the like, on the back of the panel and
behind it. The panels are preferably made the same size so that they are inter-
changeable.
In front of and immediately below the vertical panels referred to, is a fixed

page_text: desk slab P, which may or may not be of the same material as the vertical panels,
and below the front edge of this desk are other vertical panels Q and Q₁ extending
to the floor. Both the desk and the lower vertical panels are fixed to a simple
framework which we prefer to make of wrought iron. At the sides of the switch-
board we fix slabs generally of like material to those forming the face of the
board.
The framework and its panels and side, top, and desk slabs herein before
described are incombustible, and compact, and the arrangement obviates the
necessity for a passage behind the switchboard. The said switchboard can be
easily extended, is simple to erect, and cheap to make, it is strong and rigid,
and has also a good appearance.
On the vertical panels A we mount the main instruments, fittings and the
like pertaining to the generators and feeders or circuits, and on the horizontal
desk P and lower vertical panels Q Q we mount the instruments, fittings and
the like pertaining to the fields of the generators, the exciters, and the regulation
of pressure on the feeders, or circuits."
In the case of alternating current switchboards we mount the synchronizers,
synchronizing lamps, bus bar, and alternator voltmeters, on the upper horizontal
slab at the top of the switchboard. We use the centre vertical panel, or panels,
for other apparatus which may be required to suit special conditions and also
to carry the switch, or switches, for coupling the bus bars together when it is
desired to do so, and also the lever for raising and lowering the pressure
gradually on any feeder, or circuit.
The bus bars are mounted upon insulated brackets or bases bolted or otherwise
fixed to the vertical rails R behind the vertical panels.
The switchboard is suitable for both low tension and high tension currents,
continuous or alternating.
In the drawing we have shewn the detail fittings only as applied to the panels
on each side of the central panel it being understood that the details on the other
panels are similar. For high pressure alternating currents each of the generator
panels A A is provided at its upper end with a plugging arrangement P', by
means of which the generator can be connected to either of the two bus bars Bi
or B by the insertion of a two prong plug Y such as is shewn in Fig. 3. one
prong y of the plug making contact with the generator terminal on the panel,
and the other prong y² making contact with either of the two bus bars B1, B2.
(Obviously the number of bus bars can be increased according to requirements.)
Below the double plugging arrangement is mounted the generator ammeter a
and below that the main switch 2. The type of switch shewn and which we
prefer to use is that for which Letters Patent No. 2761 A.D. 1898 have been
granted to us.
Below this switch is mounted a duplex" fuse ³ having a removeable part
carrying the fusible portion with plug terminals. The fuse we prefer to use is
that for which Letters Patent No. 28443 A.D. 1896 have been granted to us.
The lower terminal of this fuse is arranged to make plug contact with one of the
alternator terminals T mounted upon an insulating base fixed to each of the
vertical rails R. A two prong plug is provided for connecting the generator to
the synchronizer and voltmeter. For this purpose one of the vacant terminals
of the duplex fuse is utilized, the two prong plug connecting it to a terminal on
the synchronizer bus bar B through an opening in the panel just below the top
fuse terminal. The generator panel thus arranged can be made "dead" or
completely disconnected from the supply and from the bus bars by the removal
of the fuse at the bottom, and the plug at the top. The panel can then,
after removal of the set screw K be swung on its hinge and every part, both of
the front and back, becomes accessible and safe to touch. The feeder panels F F
have similar fittings and can be made "dead" and be swung on their hinges in
the same manner. In these panels, the lower two prong plug which joins the
contacts behind the slots n and m Fig. 2, is used for connecting the feeder or

page_text: circuit to another bus bar which is connected to the secondary of a regulating
transformer for a purpose which is described hereafter. The field panels QQ
immediately below the generator panels have mounted on them double pole field
switches. We prefer to use the type of switch for which Letters Patent
No. 7823 A.D. 1897 have been granted to us. When desired double pole fuses
can also be conveniently fitted on to these panels. If the supply of current for
the fields of the generators is taken from a bus bar we fit the single pole or double
pole switches fuses and the like pertaining to the generators supplying current
to this bus bar, on the panels Q Q which are placed below the feeder or circuit
panels.
"
On the desk slabs P immediately below the generator panels we mount hand-
wheels a' which actuate rheostats fixed below this desk and behind the lower
front vertical panels Q. These rheostats are connected in series with the fields
of the generators and are used in the ordinary way for regulating the pressure
of the supply from the generators. On the desk P and in close proximity to the
hand wheels a' of the rheostats are mounted ammeters of the
"
marine type
which indicate the field current of the respective generators. On the desk below
the feeder panels are fitted like handwheels which are connected by gearing or
otherwise, with regulating transformers: the secondary winding of each trans-
former being connected in series with a feeder or circuit thereby affording a
means of independent regulation for each feeder, or circuit, in a way which is
well understood. Voltmeters of the "marine" type are mounted on the desk
slab in close proximity to each of these wheels.
These voltmeters indicate the pressure at distant points on the feeders or cir-
cuits, where it is desired to maintain a constant pressure. The centre panel X
has mounted upon it a switch for coupling together the two upper bus bars and
an ammeter for indicating the current, if any, flowing between the bus bars when
coupled. In the middle of this panel is a slot through which a lever passes
which is connected to a regulating transformer arranged to raise or reduce
gradually the pressure on any feeder or circuit when it is desired to switch it on
or off. The arrangement is as follows;-
-
By means of the two pronged plug for utilizing the vacant duplex fuse terminal
hereinbefore referred to a feeder, or circuit, is connected to a bus bar, 133 Fig. 4
which bus bar is connected to the secondary $3 of the above mentioned regulating
transformer, the primary of which is connected to the upper bus bar from which
the feeder or circuit is being supplied. The connections are so arranged that
the secondary of this transformer is then in parallel with the feeder or circuit,
and when the transformer is in the position of maximum secondary pressure,
the ratio of the windings is such that the secondary volts equal or exceed slightly
the volts of the supply to the feeder, or circuit from the bus-bar, the result being
that when the transformer is connected to the feeder or circuit in the way indi-
cated above, it supplies none, or very little, of the current to that feeder or circuit.
But when the feeder or circuit main switch is opened, the transformer which is
connected to the feeder or circuit side of the switch, takes all the load, which at
that moment is on the feeder or circuit. By manipulating the hand lever L,
the regulating transformer is gradually brought to the position of zero secondary
pressure, and the supply to the feeder or circuit is thus gradually reduced, and
the insulation of the cables etc. consequently protected. A feeder or circuit can
be gradually switched on by a reversal of the operations described above.
We prefer to use the regulating transformer with the improvements for which
Letters Patent No. 28442 A.D. 1896 have been granted to us.
On the top slab of the switchboard are mounted three voltmeters V1, V2, and W
which are connected respectively to bus bar B₁, bus bar B2, and the synchronizer
bus bar. When parallelling, the voltmeter W which is connected to the
synchronizer bus bar indicates the volts of the incoming alternator. There are
two synchronizers and 7 mounted on the top slab together with the synchro-
nizing lamps. One synchronizer with its lamp is for one bus bar and one is for

page_text: the other bus bar. The synchronizing transformers are arranged to make both
their primary and secondary connections through the four feet upon which they
stand, the connection being made by simple contact of the feet with terminals
mounted on the top panel and shaped to receive them. This arrangement enables
a synchronizing transformer to be quickly changed for another in the event of
its breaking down. For a system with one pole earthed, the bus bar E is the
earthed bar.
We do not confine ourselves to the exact positions of the instruments and
fittings described as the arrangement may be modified to suit special conditions.
Having now particularly described and ascertained the nature of our said in-
vention and in what manner the same is to be performed, we declare that what we
claim is:
1
1. The construction of a switchboard having a framework and arrangement
of panels substantially as hereinbefore described and shewn on accompanying
drawing, Figs. 1 and 2.
2. The construction of a switchboard with panels hinging on their lower edge
in conjunction with plugs or other form of quickly removed connection between
the bus bars or the supply terminals or both and the fittings upon the panel
substantially as hereinbefore described.
3. In a switchboard constructed with panels as described a fuse having plug
terminals for connecting the fittings on the panel to the supply to or from the
switchboard substantially in the manner herein before described.
4. In a switchboard constructed with panels as described a two-way plug for
electrically connecting the fittings on the panel to the bus bars substantially
in the manner hereinbefore described.
5. The construction of switchboard with fixed vertical rails, substantially as
herein before described and shewn on accompanying drawing, Fig. 1.
6. In a switchboard constructed with panels as described the provision of a
"V" shaped slot as a seating for the hinge pin or pivots at the lower end of
each panel, substantially as herein before described.
7. In a switchboard constructed with panels as described a lever or contact
maker for operating an alternating current regulating transformer for gradually
switching on and off the supply to feeders or circuits substantially in the manner
herein before described.
8. In a switchboard constructed with panels as described the use of one of the
vacant terminals of the duplex fuse for making connection between the machine
and the synchronizer or voltmeter or both, and between the feeder or circuit and
the regulating transformer secondary terminal, substantially in the manner,
and for the purposes, herein before described.
9. The construction of a switchboard with similar panels quickly interchange-
able, in the manner substantially as hereinbefore described.
Dated this 8th day of December 1898