Siemens Aktiengesellschaft

Metallgesellschaft Aktiengesellschaft

Helmut Schummer

Franz Neulinger

Walter Schmidt

Heinrich Winkler

Horst Daar

Gunter Mehler

Helmut Herklotz

Gerhard Donig

Gerhard Rumold

Hartmut Gaul

Richard Dallhammer

Hans-Joachim Knaak

Norbert Grass

Franz Alig

Hermann Mickal

Roland Humpfner

Heinrich Bocker

A filter short circuit is detected when the primary voltage of the high-voltage transformer drops below a specified minimum value and does not rise above the specified minimum value during a specified delay period and a filter current is greater than a specified minimum current. No current is drawn from the external current supply for a variable time delay when a filter short circuit is detected. A filter short circuit count is incremented when a filter short circuit is detected. When the count exceeds a specified, variable limit within a specified, variable time span, the indirect converter is disconnected.

Process for controlling a power supply which supplies power to an

A voltage supply for an electric filter is disclosed. The supply comprises a high-voltage rectifier, a pulsed voltage circuit including a resonant circuit and a parallel circuit of a thyristor and a diode which controls resonance in the resonant circuit. The thyristor is fired to trigger the resonant circuit and generate an oscillation which is delivered to the filter as a pulsed voltage. In order to prevent damage to the thyristor, it is fired whenever the duration of the current flowing through the diode is shorter than the thyristor recovery time.

Voltage supply with recovery protection for a thyristor

An electrostatic precipitator is supplied with a d-c voltage of variable level upon which is superimposed a series of voltage pulses. For each voltage pulse, the difference between a positive current-time area and a negative current-time area beneath a current-voltage curve is determined and maximized by changing the pulse amplitude, pulse width, pulse repetition frequency and/or the rate of pulse rise. In addition, the d-c voltage is controlled to have a value at a point of maximum slope of the function of precipitator current with respect to the magnitude of the d-c voltage.

Electrostatic precipitator power supply

In order to scrub a waste gas, for example, of foreign matter by means of an electrostatic filter, a power supply is provided which contains a converter whose output feeds the primary winding of a high-voltage transformer. The secondary winding is connected to the electrostatic filter via a high-voltage rectifier. Disposed in the intermediate circuit of the converter is a control element for the intermediate circuit current. This shields the supply network against the effects of the power converter commutations and of short-circuits in the filter to a great extent. A limiter for the filter voltage and a temporary separation of the transformer from the inverter in case of filter short-circuits may be provided to reduce the stress on the components which can be made small if a high-frequency working cycle for the setter and the inverter is used.

Power supply for an electrostatic filter

In an electrostatic precipitator which is supplied with energy in the form of d.c. voltage pulses or of a d.c. voltage and superposed pulses, the energy supply is optimized and reverse corona discharges are avoided by use of a method in which energy at the highest possible rate is supplied to the electrostatic precipitator during the pulsing period and the total energy consumption of the electrostatic precipitator required to achieve in the pure gas a predetermined maximum dust content is minimized in that the pulse parameters are optimized and the application of pulses is interrupted for the longest possible non-pulsing time which is consistent with the predetermined maximum dust content of the pure gas.

Method of automatically controlling an electrostatic precipitator

An electrostatic precipitator is fed high voltage pulses by a pulse generating circuit including a high voltage transformer and a first thyristor switch connected in series with a primary winding of the transformer. Magnetic saturation of the core of the high voltage transformer is prevented by recurrently short circuiting the primary winding of the transformer by means of a second thyristor switch connected in parallel to the primary winding. The second thyristor switch is closed for a period of time extending from a first instant following a high voltage pulse crest to a second instant at or before the start of a pulse generating cycle subsequent to the pulse crest.

Method and apparatus for supplying an electrostatic precipitator with

A method for detecting breakdowns in an electrostatic filter in which single measured values of equal phase of successive half waves of the filter voltage and crest values of successive half waves of the primary current are compared with one another and in which the differences of the measured values at which a breakdown signal is delivered are made dependent on the existing filter voltage or the primary current.

Method for detecting breakdowns in an electrostatic filter

The optimum knock frequency of an electrofilter installation consisting of several filters is determined. Each filter includes a microcomputer controller and a knocking device. The knock frequency is controlled by a superimposed master computer and the optimum knock frequency for a given knock frequency, varying the frequency by the master computer, again measuring the long-term average of the dust loading, and continuing to change the frequency and measure the dust loading until the dust loading value reaches a minimum.

Method for optimizing the knock frequency of an electrofilter system

A system for controlling the voltage of an electrofilter of the type which, after a voltage breakdown, substantially reduces the magnitude of the electrofilter voltage. After a predetermined deionization time, the filter voltage is raised to a new level which is lower than the filter voltage at which the initial voltage breakdown occurred, by a predetermined amount. The filter voltage is subsequently raised in accordance with a predetermined voltage-time function until a further voltage breakdown occurs. The electrofilter voltage is controlled by a microcomputer system in accordance with stored control parameter values. The stored control parameter values are advantageously recalled to control the electrofilter voltage in response to the operating state of a plant in which the electrofilter is employed. In plants wherein a plurality of electrofilters are employed, each such electrofilter is controlled by an associated microcomputer system, the plural microcomputer systems being controlled by a central pilot computer. The central pilot computer of the plant computes strategies which enhance the energy efficiency of the overall electrofilter purification system.

System for controlling the voltage of an electrofilter

A method for operating an electrostatic precipitator with a DC voltage and superimposed pulses or superimposed AC voltage in which individual parameters such as amplitudes, pulse repetition frequency, pulse width, etc. are iteratively and continuously varied in such a manner that the sum of the pulse and the DC voltage power approaches a minimum. A computer which calculates, from the dust load and the absorbed electric energies of the filter, control commands for the DC and pulse voltage source is used for this purpose.

Method of operating an electrostatic precipitator

A system for automatically controlling the voltage of an electrostatic filter with respect to its breakdown voltage limit. The detection of secondary voltage breakdowns which occur within a post-breakdown time period after an initial voltage breakdown cause the filter voltage to be lowered to zero value. After a deionizing time period, the filter voltage is gradually raised during a predetermined rise time period until it reaches a new value. The duration of the deionizing time period and the rise time period may be advantageously computed in response to the history of voltage breakdowns, by a microcomputer system.

System for automatically controlling the breakdown voltage limit of an

The automatic recording of the current-voltage characteristic of an electrostatic filter in which the characteristic obtained upon stepwise variation of the control is displayed to the operating personnel and at the same time saturation phenomena and voltage maxima are picked up.

Method for determining the filter current limit of an electrostatic

A method for controlling the voltage of an electrostatic filter at the breakdown limit in which, when a breakdown occurs, the voltage is reduced by an amount which is determined by the breakdown voltage and the prior history of the breakdown and the waiting time to the next increase of the filter voltage is made dependent on the ratio of the voltages at successive breakdowns by comparing voltage amplitudes which immediately precede the breakdowns.

Method for automatic control of the voltage of an electrostatic filter

A detector for detecting breakdowns on the high-voltage side of an electric precipitator, the voltage of which is supplied from an a-c network through a thyristor control circuit, a high-voltage transformer and a rectifier. The improvement of the invention comprises means for continuously comparing characteristic parameters of successive half-waves of variations of the voltage at the precipitator. A predetermined deviation of the characteristic parameters comprises a criterion for determining a breakdown of the precipitator voltage.

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Heusenstamm, Germany

Helmut Schummer