Electrical apparatus to control the extinction angle of valves of a converter

Claim 2

An extinction angle control for controlling the extinction angle of valves of a converter comprising a. control means for varying the firing angle of firing pulses applied to all valves of the converter in response to changes in system operating conditions comprising b. condition pulse generating means for generating an electrical condition pulse at the expiration of a predetermined period following cessation of conduction of load current in a valve, detection means for detecting and comparing the existence of said condition pulse with a predetermined time reference and, encroachment signalling means producing an encroachment signal when said condition pulse occurs after said time reference.

Claim 3

A control circuit for controlling the firing angle of the firing pulses supplied to the valves of a converter in a certain predetermined logical sequence comprising, adjustment means for changing the firing angle of firing pulses supplied to all the valves in response to changes in a basic function, and current conduction indicating means associated with each valve to produce an electric current conduction signal when a valve in said converter is carrying load current, and preset extinction angle pulse (PEAP) generating means for generating a PEAP at a preselectably variable delay from the end of said current conduction signal, and conduction indicating signal (CIS) means generating an CIS in response to the generation of a PEAP signal, and continuing until a predetermined end stop is reached, and detecting means to detect and compare the beginning of said CIS with a predetermined time reference to determine the presence of said CIS signal before or after said reference, and encroachment signal generating means for producing an encroachment signal when said detecting means detects the beginning of said CIS after said time reference.

Claim 4

A control circuit for controlling the firing angle of the firing pulses supplied to the valves of a converter in a certain predetermined logical sequence comprising, adjustment means for changing the firing angle of firing pulses supplied to all the valves in response to changes in a basic function, and current conduction indicating means associated with each valve to produce an electric current conduction signal when a valve in said converter is carrying load current, and preset extinction angle pulse (PEAP) generating means for generating a PEAP at a preselectably variable delay from the end of said current conduction signal, and conduction indicating signal (CIS) means generating an CIS in response to the generation of a PEAP signal, and continuing until a predetermined end stop is reached, and detecting means to detect and compare the beginning of said CIS with a predetermined time reference to determine the presence of said CIS signal before or after said reference, and encroachment signal generating means for producing an encroachment signal when said detecting means detects the beginning of said CIS after said time reference.

Claim 5

A control circuit for controlling the firing angle of the firing pulses supplied to the valves of a converter in a certain predetermined logical sequence comprising; adjUstment means for changing the firing angle of firing pulses supplied to all valves in the converter in response to changes in a basic function and current conduction indicating means associated with each valve to produce an electric current conduction signal when a valve in said converter is carrying load current and, condition pulse generating means for generating an electrical condition pulse at the expiration of a predetermined period following cessation of conduction of load current in a valve and detecting means for detecting and comparing the existence of said condition pulse with a predetermined time reference and encroachment detecting and signalling means producing an encroachment signal when said condition pulse occurs in time after said time reference, said encroachment signal having a duration beginning at said time reference and ending at the beginning of said condition pulse, said adjustment means receiving said encroachment signal, said adjustment means changing the firing angle of the firing pulses to all valves in the converter by an amount proportional to the duration of said encroachment signal.

Claim 6

A control circuit for controlling the firing angle of the firing pulses supplied to the valves of a converter in a certain predetermined logical sequence comprising; adjUstment means for changing the firing angle of firing pulses supplied to all valves in the converter in response to changes in a basic function and current conduction indicating means associated with each valve to produce an electric current conduction signal when a valve in said converter is carrying load current and, condition pulse generating means for generating an electrical condition pulse at the expiration of a predetermined period following cessation of conduction of load current in a valve and detecting means for detecting and comparing the existence of said condition pulse with a predetermined time reference and encroachment detecting and signalling means producing an encroachment signal when said condition pulse occurs in time after said time reference, said encroachment signal having a duration beginning at said time reference and ending at the beginning of said condition pulse, said adjustment means receiving said encroachment signal, said adjustment means changing the firing angle of the firing pulses to all valves in the converter by an amount proportional to the duration of said encroachment signal.