Title of Invention

AUTOMATIC TRANSFEER SWITCH SYSTEMS AND CONTROLLERS

Abstract An automatic transfer switch (ATS) controller (40) is disclosed which includes a power supply circuit to regulate and filter input power, a transformer to convert utility (12) and generator (14) power sources into power supply voltages and voltage sensing sources and a voltage sense signal conditioning circuit. Controller further implements a solenoid driver circuit to drive automatic transfer switch solenoids, an embedded microcontroller (42) configured to monitor utility and generator voltages and a user interface (46) interfaced to said microcontroller for operator entry of instructions. A LED indicator is included and is configured to verify user interface entries and overall operation of the controller and ATS system (FIG. - 1)
Full Text BACKGROUND OF THE INVENTION
This invention relates generally to electrical switches and, more
particularly, to automatic transfer switches and control thereof.
Many businesses use transfer switches for switching power sources, for
example, from a public utility source to a private secondary supply, automatically.
within a matter of seconds. Critical load businesses, such as, for example, hospitals,
airport radar towers, and high volume data centers are dependent upon automatic
transfer switches to provide continuous power. Transfer switches typically utilize a
plurality of contacts that can be open or closed.
Typically, automatic transfer switches are controlled using relay logic,
programmable logic controllers (PLCs) or embedded controllers. In known systems,
the embedded controller monitors the public utility power source for a fault condition.
Upon recognizing any one of a number of faults with the utility power, the embedded
controller is configured to switch in the secondary source of power, typically a
generator, via the transfer switches.
Known automatic transfer switch controllers incorporate external
components to accomplish the control task and require hardware and software
redesigns when making input/output (I/O) changes. Further, known automatic transfer
switch controllers are unable to communicate with external devices for software
selection of options.
Accordingly, it would be desirable to provide systems for automatic
transfer switch control which eliminate external components and provide flexibility
for I/O circuit redesign. It would be further desirable to have an automatic transfer
switch controller with a communications interface to enable and select software
options from an external device.
BRIEF SUMMARY OF THE INVENTION
An automatic transfer switch controller includes a power supply circuit
to regulate and filter input power. Also included is a transformer to convert utility and
generator power sources into power supply voltages and voltage sensing sources for
the controller. A voltage sense signal conditioning circuit is included as is a solenoid
driver circuit used to drive automatic transfer switch solenoids. The controller uses an
embedded microcontroller to monitor utility and generator voltages which is
interfaced to a user interface for operator entry of instructions. An LED indicator
interfaced to said microcontroller is used to indicate operator entry of instructions at
the operator interface.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a simplified schematic showing electrical routing within an
automatic transfer switch system; and
Figure 2 is a block diagram of an automatic transfer switch controller.
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 is a simplified schematic diagram 10 showing electrical
routing within an automatic transfer switch (ATS) system. Included in diagram 10 are
a utility source 12 and a generator source 14. Each of utility source l2 and generator
source 14 are routed through circuit breakers 16 to a transfer switch 18. Transfer
switch 18 is configured to route electrical power from utility source 12 through
transfer switch 18 to a main breaker panel 20, through which electricity is distributed
throughout a facility. Transfer switch 18 is further configured with a controller (not
shown) to monitor the power from utility source 12 for power quality, for example
voltage, power factor, electrical noise and the like. When the transfer switch
controller senses a problem with power quality, based upon preset limits, the transfer
switch controller commands transfer switch 18 to switch to electrical power from
generator source 14, on a temporary basis, until the transfer switch controller senses
that the power quality from utility source 12 has returned to an acceptable level.
Figure 2 is a block diagram of an automatic transfer switch controller
40. Controller 40 includes a microcontroller 42, a memory 44, a user interface 46, a
power input section 48, an output section 50 which is configured to command one or
more transfer switches 18 (shown in Figure 1) to go to power from a generator source
or to return to a utility source of power. Controller 40 also includes a configuration
section 52, a communications port 54 and a multi-function input/output (I/O) port 56
described below in more detail.
The term microcontroller, as used herein, also refers to
microprocessors, reduced instruction set circuits (RISC), application specific
integrated circuits (ASICs), logic circuits, and any other circuit or processor capable
of executing the programs described above.
Controller 40 is a low cost, high performance ATS controller with
software selectable options. In one exemplary embodiment, software options are to be
enabled or disabled through the use of a factory configuration program via port 54,
which is for example, an RS232 port.
Controller 40 is configured with external connections (not shown in
Figure 2) to allow for adaptation of multiple function input/output (I/O) boards. I/O
boards give controller 40 a modular configuration where different options can be
made available to the end user if needed.
In one exemplary embodiment, functions of controller 40 are
implemented on a main control circuit board which includes control and conditioning
circuits as described below.
Power input section 48 includes transformers to convert power from
utility source and generator source 14 (both shown in Figure 1) into power supply
1 voltages for powering controller 40 and into voltages to be sensed by controller 40.
I Power input section 48 regulates and filters raw supply voltages from the transformers
before it is applied to the main control board of controller 40 and any optional I/O
boards such that correct operating voltages and currents are applied to such boards.
Power input section 48 further includes a voltage sense signal
conditioning circuit which uses low pass filtering techniques to remove all unwanted
noise from the raw voltage supply before it is applied to analog-to-digital converter
(ADC) pins on microcontroller 42. Filtering allows controller 40 to correctly sense
voltage and frequency when utility source 12 or generator source 14 contain large
amounts of harmonic distortion.
In another exemplary embodiment of controller 40, output section 50 is
configured as a solenoid driver circuit which includes two options of solenoid drivers,
both of which are implemented on the main control board. A first solenoid driver
option is configured with on-board relays when the utility and generator power
sources are 240Vac and below. A second solenoid driver option is configured with
solid state devices when the utility and generator power sources are greater than
240Vac, but less than 600 Vac. The solenoid driver circuit is used to control the
power supplied to an ATS drive solenoid which causes swithcing from one electrical
power source to another in transfer switch 18 (shown in Figure 1).
Using user interface 46 a user can momentarily energize a normal
output causing the ATS to transfer to normal position, the position where utility power
is used. Momentarily energizing an emergency output causes the ATS to transfer to
the position where generator power is used. In order to protect the ATS drive
solenoid from damage, a solenoid saver scheme is implemented in controller 40 which
controls the maximum on time and the number of tries a drive solenoid can be
energized for before shutting down the drive circuit and initiating a diagnostic mode.
All functions on the main control board are controlled by
microcontroller 42 which uses custom written firmware to monitor the utility and
generator voltages and frequency, monitor user interface updating indicator LEDs on
user interface 46, perform real time clock functions, monitor ATS position and control
the ATS. Microcontroller 42 also monitors and controls all external I/O connections
used to control any auxiliary I/O boards. In a further embodiment, controller 40 is
configured with a generator cool down timer, a geneator warmup timer, a loss of
power delay timer, a generator fail-to-start timer, a generator crank timer, a generator
pause timer, a generator overload timer and an utility stabilization before switchback
timer.
Controller 40 includes a configuration section 52. In one embodiment,
configuration section 52 includes a jumper panel. Jumpers are installed by a user to
select one of a seven, 14, 21, or 28 day cycle for a built in ATS exerciser. The
exerciser period can be adjusted for seven, 14, 21, or 28 days by selecting the
appropriate jumpers setting located on the main control board.
Configuration section 52 further includes jumper selectable voltage and
frequency selections. The voltage controller 40 can sense is selectable from 120, 208,
220, and 240 Vac through the use of the correct jumper settings. Voltage ranges in the
380, 415, 440, and 480Vac are also selectable, but require that a different transformer
be used in controller 40. Jumpers are also available for frequency selections of 50 Hz
and 60 Hz.
Controller 40 is further configured with a passive load shed option
which, when coupled with a load shed I/O option board will disconnect certain high
kilowatt loads before the controller transfers loads from utility power to generator
power, thereby preventing unwanted loads from over loading generator 14.
In another embodiment, controller 40 is configurable with a generator
control board (not shown) option which is an optional I/O board that connects to the
main control board and contains I/O functions which are accessible at I/O port 56.
Examples of I/O functions include, but are not limited to oil pressure sensing,
temperature sensing, and a set of dry contacts for starter motor control including a
fuel/run contact output and a start contact output. When a generator control board is
included in controller 40, a software control bit is enabled to allow access to the board
I/O functions.
In still another embodiment, controller 40 is configurable with a three
phase sense board (not shown). The three-phase sense board is an optional I/O board
that expands controller 40 from single-phase voltage sensing to three-phase voltage
sensing on both utility and generator power sources. The three-phase sense board
contains all of the necessary conditioning circuitry necessary for proper voltage and
frequency detection.
Controller 40 solves problems present in known controllers. Such
problems include external relay transformer boxes separate form the controller, a need
for an external exerciser clock and the ability to make I/O changes without complete
redesign of the ATS controller. In addition, controller 40 locates all ATS control
components and voltage conditioning components on a main control board, thereby
allowing for other I/O functionality to be implemented on option boards as described
above.
While the invention has been described in terms of various specific
embodiments, those skilled in the art will recognize that the invention can be practiced
with modification within the spirit and scope of the claims.
We Claim
1. An automatic transfer switch controller (40) comprising:
a power supply circuit to regulate and fitter input power;
at least one transformer to convert utility (12) and generator (14)
power sources Into power supply voltages and voltage sensing sources;
a voltage sense signal conditioning circuit;
a solenoid driver circuit to drive automatic transfer switch
solenoids;
an embedded microcontroller (42) configured to control logic
functions and to monitor utility and generator voltages and frequencies;
a user interface (46) to said microcontroller for operator entry of
instructions; and
at least one LED indicator interfaced to said microcontroller to
indicate operator entry of instructions at said user interface.
2. A controller (40) as claimed in claim 1, wherein said microcontroller (42)
comprises at least one analog-to-digital converter.
3. A controller (40) as claimed in claim 2, wherein said voltage sense signal
conditioning circuit comprises low pass filters configured to remove noise
from the power supply thereby enabling said microcontroller (42) analog-
to-digital converter to correctly sense voltage and frequency.
4. A controller (40) as claimed in claim 1, wherein said solenoid driver circuit
is configured with relays for powering automatic transfer switch drive
solenoids.
5. A controller (40) as claimed in claim 1, wherein said solenoid driver circuit
is configured with solid state devices for powering automatic transfer
switch drive solenoids.
6. A controller (40) as claimed in claim 1, wherein said microcontroller (42) is
configured to recognize jumper selections for an exerciser clock adjustable
for settings for a preselected number of days.
7. A controller (40) as claimed in claim 1, wherein said microcontroller (42) is
configured to recognize jumper selections for supply voltages for at least
one of 120 VAC, 208 VAC, 220 VAC and 240 VAC.
8. A controller (40) as claimed in claim 1, wherein said transformer is
configured for supply voltages of at least one of 380 VAC, 415 VAC, 440
VAC and 480 VAC, said microcontroller (42) is configured to recognize
jumper selections for supply voltages for at least one of 380 VAC, 415
VAC, 440 VAC and 480 VAC.
9. A controller (40) as claimed in claim 1, comprising a generator control
board configured to interface with said microcontroller (42) and to sense
at least one of oil pressure and temperature.
10.A controller (40) as claimed in claim 9, wherein said generator control
board is configured with a set of dry contact outputs for starter motor
control including at least one of a fuel/run contact output and a start
contact output.
11. A controller (40) as claimed in claim 1, comprising a three phase sense
board configured to expand single phase sensing capabilities of said
controller to three phase sensing on utility (12) and generator (14)
sources.
12.A controller (40) as claimed in claim 1, comprising a bad shed I/O option
board configured to disconnect loads before said controller transfer loads
to a generator power source (14), preventing generator over load.
13. A controller (40) as claimed in claim 1, wherein said microcontroller (42) is
configured with at least one of a generator cool down timer, a generator
warmup timer, a loss of power delay timer, a generator fail-to-start timer,
a generator crank timer, a generator pause timer, a generator overload
timer and an utility stabilization before switchback timer.
14.A controller (40) as claimed in claim 1, wherein said microcontroller (42) is
configured to recognize jumper selections for frequencies of 50 Hz and 60
Hz.
15.An automatic transfer switch system comprising:
an input (48) configured to be connected to a utility power source
(12);
an input configured to be connected to a generator power source
(14);
a transfer switch (18) configured to switch a load from said utility
power source to said generator power source and further configured to
switch the bad back to said utility power source; and
an automatic transfer switch controller (40).
Visible diode laser based diameter gauge with large stand off distance adapted
for non-contact method of on-line measurement especially for use in stand rolling
mills having means for extending the distance between source and detection
upped about 5 mitres or so, visible laser diode for simplified installation and
adapted for large stand-off measurement, means for detecting the presence and
absence of moving rod/bars in steel rolling mills and the like, means for
estimating the ovality/shape of the rod. The non-contact method of on-line
diameter measurement is very much useful in steel rolling mills for bar and rod
products in measuring the diameter/width of the rod/bar. It is also useful in wire
and cable industry for on-line inspection and measurement of the diameter of
cables and wires. It can also be applied in cigarette industry for measuring the
circumference of the cigarettes. The non-contact method is useful where the
object is moving or very hot.

Documents:


Patent Number 216887
Indian Patent Application Number 632/CAL/2001
PG Journal Number 12/2008
Publication Date 21-Mar-2008
Grant Date 19-Mar-2008
Date of Filing 09-Nov-2001
Name of Patentee GENERAL ELECTRIC COMPANY
Applicant Address ONE RIVER ROAD SCHENECTADY NEW YORK 12345 USA.
Inventors:
# Inventor's Name Inventor's Address
1 RADUSEWICZ PETER J. 13950 WEST DORAL LANE LOCKPORT ILLINOIS 60414 USA.
PCT International Classification Number B/61 22/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/751 2000-12-29 U.S.A.