RU-2861408-C1 - PROTECTION DEVICE FOR DC ELECTRICAL DISTRIBUTION BOARD AGAINST INTERNAL ARC SHORT CIRCUITS

RU2861408C1RU 2861408 C1RU2861408 C1RU 2861408C1RU-2861408-C1

Abstract

FIELD: electricity. SUBSTANCE: technical solution of a protection device for a DC electrical distribution board against internal arc short circuits relates to the field of electrical engineering, namely to relay protection of ship (vessel) DC electrical distribution boards against internal arc short circuits. EFFECT: increasing the sensitivity of the protection device due to the operation of the protection device at arc short circuit currents comparable to the rated load current of the source, which is achieved by introducing a DC voltage harmonic sensor into the protection device, and increasing reliability by preventing the protection device from tripping at the rated load of the power supply even in the event of abnormal operation of the arc sensor (for example, when light enters the distribution board during routine maintenance without disconnecting the voltage). 3 cl, 5 dwg

Inventors

BORISOV LEONID FILIPPOVICH
Ageev Ivan Nikolaevich
Zorin Vasilij Valerevich
GRIGOREV VALENTIN GRIGOREVICH

Dates

Publication Date: 20260505
Application Date: 20251107

Claims (3)

1. A device for protecting a direct current electrical distribution board from internal arc short circuits, comprising a photo sensor connected to the first input of an AND logic element, a voltage sensor, a monostable multivibrator, an AND logic element, and an output element connected in series, characterized in that the voltage sensor is made in the form of a DC voltage harmonic sensor, connected between the DC network and the monostable multivibrator, with the ability to tune out the response from external high-frequency interference and from standard switching modes.
2. The device according to paragraph 1, characterized in that the voltage harmonic sensor is made using a high-pass filter.
3. The device according to paragraph 1, characterized in that the voltage harmonic sensor is made using a bandpass filter.

Description

The claimed technical solution relates to the field of electrical engineering, namely to relay protection of DC distribution boards with voltage up to 1000 V, including marine (shipboard) ones, from arc short circuits (hereinafter referred to as short circuits). A device for detecting and localizing arc faults in electrical installations is known, according to German patent DE 1126011, published March 22, 1962, comprising a voltage converter connected to the primary network, the output of which is connected to a voltage asymmetry sensor and a voltage deviation sensor. The output of the voltage asymmetry sensor is connected to the first input of a first two-way AND gate, the second input of which is connected to the output of a photoelectric measuring element. The output of the voltage deviation sensor is connected to the first input of a second two-way AND gate, the second input of which, in turn, is connected to the output of the photoelectric measuring element. The disadvantages of the known device are: - the device is not intended to protect against arc short circuits in a DC network; - the possibility of false triggering of the device due to light radiation from arc-extinguishing chambers of circuit breakers when disconnecting external short circuits. The closest arc fault protection device, adopted as a prototype, is the protection device according to the author's certificate SU 604077, published on April 25, 1978, containing a series-connected voltage (deviation) sensor and a monostable multivibrator, the output of which is connected to an AND logic element, the second input of which is connected to the output of a photosensor. The output of the AND element is connected to an output element, which, when triggered, acts on the independent tripping device of the circuit breaker. The protection device is triggered when signals from both sensors appear simultaneously. A disadvantage of this device is its insufficient sensitivity to arc faults, namely, failure to operate at arc fault current (and hence voltage) values close to (comparable to) the rated current (voltage) of the power source. This is due to the fact that during arc faults, the arc column can significantly limit the short-circuit current. Almost any short circuit in ship electrical systems is a short circuit caused by an electric arc (Electrical Protection of Ship Electrical Equipment / E.A. Kalyazin et al. - Leningrad: Sudostroenie, 1983. - 240 p.). The setting of a voltage sensor operating without time delay, as part of a switchboard arc protection system, as well as, for example, a generator undervoltage protection relay, should be in the range of (0.3-0.7) Unom, where Unom is the nominal voltage of the switchboard busbars. (Rules for the Classification and Construction of Sea-Going Vessels. Part XI. Electrical Equipment. St. Petersburg. 2023). With this setting, the voltage sensor can only operate at currents several times greater than the nominal value. The aim of the invention is to create an arc fault protection device with increased sensitivity and reliability by eliminating the failure of the protection device to operate at arc fault currents comparable to the rated load currents of the power source or feeder, which results in a technical result of increased sensitivity and reliability at arc fault currents comparable to the rated load current of the power source. The technical result is achieved by a device for protecting a DC electrical distribution board from internal arc short circuits, comprising a photosensor connected to the first input of an AND logic element, a voltage sensor, a monostable multivibrator, and an AND logic element connected in series. The voltage sensor is configured as a DC voltage harmonic sensor, connected between the DC network and the monostable multivibrator, with the ability to tune out external high-frequency interference and normal switching modes. The voltage harmonic sensor is implemented using a high-pass filter. The voltage harmonic sensor is implemented using a bandpass filter. The essence of the claimed technical solution is explained by graphic materials, which depict: block diagram of the claimed arc short circuit protection device in Fig. 1, Timing diagrams of the device operation are shown in Fig. 2. The device contains a series-connected DC voltage harmonic sensor 2 and a monostable multivibrator 3, the output of which is connected to the second input of the AND logical element 4, the first input of which is connected to the photo sensor 1. The output of the AND element 4 is connected to the output element 5, which acts upon actuation on the independent release of the circuit breaker (CB). Photosensor 1 can be made on the basis of a photodiode, photothyristor or photoresistor and a threshold element at the output using an operational amplifier (hereinafter OP). Monostable multivibrator 3 and AND gate 4 can be implemented using an op amp. Output element 5 can be implemented using a thyristor