Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Reexamination Certificate
2000-07-17
2002-08-27
Sherry, Michael J. (Department: 2829)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
C324S426000, C204S228400, C361S093100
Reexamination Certificate
active
06441624
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to an experimenting apparatus for fuel cell technology, which contains a fuel cell having a fuel source and, for experimental determination of the power and of the characteristic of the fuel cell, a number of resistors as electrical loads as well as an ammeter and a voltmeter.
In terms of teaching and training, the measurement of the power and the characteristic of fuel cells are among the experiments which are normally carried out in order to illustrate the principles of fuel cell technology to trainees. The experimental apparatuses used for this purpose use conventional multimeters with numerous measurement ranges for current, voltage and resistance, whose performance range is very wide and thus, in fact, makes it rather difficult, particularly for students in lower classes, to carry out experiments. The determination of the characteristic, for which the test equipment described above is used to measure the voltage for various resistances and is plotted against the current level, is associated with additional difficulties for the trainee since numerous resistors, which are connected by rotary or slide switches to form resistor decades, are used for this purpose having an adjustment range and an accuracy which make it hard to carry out experiments easily and clearly and, furthermore, which are associated with high procurement costs.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an experimenting apparatus for fuel cell technology, that overcomes the above-mentioned disadvantages of the prior art devices of this general type, which can be operated easily and clearly and can be provided at low cost.
With the foregoing and other objects in view there is provided, in accordance with the invention, an experimenting apparatus for fuel cell technology containing a fuel cell having a fuel source and operating characteristics including a current range, a voltage range, and a power range. At least three and a maximum of 15 resistors having resistances are selectively connected to the fuel cell and function as electrical loads. The resistances correspond to an expected profile of the operating characteristics of the fuel cell. An ammeter is connected to the fuel cell and has a maximum of two measurement ranges corresponding to the power range, the voltage range and the current range of the fuel cell. A voltmeter having a maximum of two measurement ranges corresponding to the power range, the current range, and the voltage range of the fuel cell is connected to the fuel cell. The resistors, the ammeter and the voltmeter are provided for an experimental determination of the operating characteristics of the fuel cell.
The fundamental idea of the invention is that an ammeter and a voltmeter with a maximum of two measurement ranges are provided, corresponding to the power range of the fuel cell or a number of fuel cells connected in parallel or in series and at least three, but a maximum of 15 resistors, each having a resistance matched to the expected characteristic profile.
An experimental apparatus which is limited in terms of test equipment and resistors in such a way can on the one hand be provided at low cost and makes it considerably easier to carry out experiments since, depending on the performance range, only one of a maximum of two test equipment measurement ranges need be selected. Therefore, only a small number of resistors with steps corresponding to the expected characteristic profile are required to determine the characteristic of the fuel cell. When carrying out experiments, the trainees can concentrate on the correct layout of the measurement configuration in conjunction with the fuel cell, the fuel source and the load, and carrying out the measurement itself and do not have to concern themselves with the complicated choice of numerous measurement ranges for the current, voltage and resistance required with conventional multimeters, and which may considerably influence how the experiment is carried out by those with little prior training.
A feature which considerably simplifies the experimenting apparatus is to use only three resistors, which are sufficient to achieve sufficiently accurate results for teaching purposes. A further important feature is that at least one resistance between 0.5 and 5 &OHgr;, one resistance between 5 and 50 &OHgr; and one resistance between 50 and 500 &OHgr; are located in a resistor chain. In general, the resistances of the resistors are in steps between 0.5 and 600 ohms. Alternatively, the number of the resistors can be twelve resistors having resistance values of 0.5, 1, 2, 3, 5, 10, 20, 50, 100, 200, 400 and 600 ohms.
In accordance with an added feature of the invention, the ammeter has a first measurement range with maximum values of up to 0.5 amperes, and a second measurement range with maximum values between 0.5 and 5 amperes for measuring a current. Accordingly, the voltmeter also has a first measurement range with maximum values of up to 2 volts, and a second measurement range with maximum values between 5 and 20 volts for measuring a voltage.
In accordance with an additional feature of the invention, there is a lamp and an electric motor as further electrical loads that are selectively connected to the fuel cell.
In an advantageous development of the invention, the resistors and the ammeter are disposed on the same board, and are preferably linked by a rotary switch. Connecting sockets for the fuel cell and the voltmeter are also provided on the board. More specifically, the rotary switch fitted on the board, the electrical loads, the further electrical loads and the ammeter are disposed and electrically connected to one another on the board. The electrical loads and the further electrical loads are connected to the rotary switch and selectively connected to the fuel cell through the rotary switch. The board has a short-circuit terminal and an open-circuit terminal connected to the rotary switch. The fuel cell can be switched to the short-circuited terminal through the rotary switch for testing a short-circuit condition, and the fuel cell can be switched to the open-circuit terminal being open contacts for measuring a no-load voltage.
The board, on which other electrical loads, such as a lamp and/or an electric motor, can be fitted, is preferably accommodated in a housing in order to protect the components disposed on it.
In accordance with another feature of the invention, the fuel source is an electrolyzer that is to be connected to a solar module and/or a gas reservoir.
In accordance with a concomitant feature of the invention, the fuel cell is one of a plurality of fuel cells and the two measurement ranges of the ammeter and the voltmeter are configured for the characteristics of the plurality of fuel cells.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an experimenting apparatus for fuel cell technology, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
REFERENCES:
patent: 3909708 (1975-09-01), Champlin
patent: 4770026 (1988-09-01), Wolf
patent: 4816768 (1989-03-01), Champlin
patent: 5512831 (1996-04-01), Cisar
Bronold Matthias
Colell Henrik
Greenberg Laurence A.
Heliocentris Energiesysteme GmbH
Locher Ralph E.
Nguyen Trung
Sherry Michael J.
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