RU24893U1 - NEUTRAL PARTIAL EARTHING COMPARTMENT CABINET - Google Patents

Description

NEUTRAL PARTIAL EARTHING COMPARTMENT CABINET.

The useful model relates to electrical engineering, to special-purpose complete devices for partial neutral grounding in electrical networks of own needs of 6 and 10 kV thermal, nuclear and other types of power plants, as well as at 6-10 kV power substations of power systems, industrial enterprises, including oil and gas deposits, metro, urban transport and other electric networks with a voltage of 6-10 kV.

The cabinet of the complete neutral partial grounding device (hereinafter referred to as SHZN) is intended for connection to the section of any switchgear with a voltage of 6-10 kV, including K-104N K-59, K-63, KRU2-6, KRU2-10 complete switchgear , K-XXVI, KR10 / 31.5, KE-6 and other series.

The ShZN cabinet can be installed either at the ends of the switchgear section of the above series, or stand separately in the switchgear room, where there is free space.

The design of the ShZN cabinet in overall and installation dimensions does not differ significantly from the K-104M cabinets.

The purpose of creating a useful model is to reduce the damage to the insulation of electrical equipment of current collectors from overvoltages during single-phase short circuits to the ground, thereby extending the service life of electric motors and other current collectors.

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Currently, predominantly insulated neutral is used in power grids of all types of power plants and electrical installations with a voltage of 6-10 kV, in which, in the event of a single-phase short circuit to ground, a current flows through the fault, the value of which is determined by the total capacity of the power grid.

In such networks, the steady-state current of a single-phase circuit can vary from tenths of an ampere to 12-15A and vpp.

As a rule, the process of a single-phase earth fault starts with an alternating electric arc fault (multiple cycles of “burning - extinction of the arc) and is accompanied by significant surges of capacitive currents that contain packets of high-frequency pulses. In this case, overvoltages dangerous to the insulation of electrical equipment arise.

Existing current protection cannot detect damaged connections with the required reliability due to insufficient sensitivity.

Operational switching and considerable time are required to determine the damaged state.

The ShZN cabinet provides the elimination of these shortcomings due to the partial neutral grounding in the electric networks of 6-10 kV of the auxiliary needs of the electric stations and the above substations.

Partial grounding of the neutral is carried out by connecting to the prefabricated busbars, each section indicated above the switchgear at only one point of an additional grounding transformer with a capacity of 63 kVA, the high voltage winding of which is connected to the "star with the output neutral.

A measuring current transformer is included in the neutral circuit, the neutral is grounded through a block of resistors. The low voltage (LV) winding is connected in a “triangle and is not involved in the SHZN circuit, surge arresters (OGSh) are connected to the terminals of the transformer YOU.

On all connections of the switchgear section, from which the SHZN is powered, zero-sequence relay protection is installed, which works with a single-phase earth fault from current transformers, with the effect of disconnecting these connections without delay.

In normal operating mode, the switchgear of the switchgear section is constantly on.

As the main request for the additional transformer, a current cutoff is installed in the switch cabinet.

The ShZN cabinet provides cable power input.

Figure 1 shows the housing of the cabinet ШЗН - the main view and the rear view, which is a metal prefabricated-welded construction frame 1, on which the door 2 is mounted and the relay cabinet 3 is placed, if necessary. In the compartment 4 there is a transformer 5 for neutral grounding, a resistor block 6 with an equivalent resistance of 100 Ohms (for a 6 kV network), a current transformer 7 and a non-linear surge suppressor 8, the need for installation and the parameters of which are determined by the customer.

To facilitate rolling out and driving in, the transformer for earthing the neutral is mounted on a frame with wheels 9.

about.

  {ff -3Application of ShZN cabinets ensures reliable operation of electric motors and other current collectors against overvoltage during single-phase short circuits to the ground, and thereby reduces the damage to insulation of electrical equipment, which significantly prolongs the life of current collectors.

The company has developed technical documentation and manufactured cabinets for delivery to customers.

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-4 FORMULA

Claims (3)

1. The cabinet of the complete neutral partial grounding device, consisting of a metal prefabricated welded frame, on which the door is mounted and a relay cabinet can be placed, if necessary, characterized in that a transformer for neutral grounding is connected to the cabinet compartment connected to the resistor block with equivalent resistance 100 Ohm (for a 6 kV network) or 150 Ohm (for a 10 kV network), with a current transformer and non-linear surge suppressor (SPD).  2. The cabinet of the complete device according to claim 1, characterized in that the high voltage winding (HV) of the transformer is connected to a "star", the neutral of the HV transformer winding is grounded through a block of resistors, and surge arresters are connected to the terminals of the high voltage windings, if necessary. 3. The cabinet of the complete device according to claim 1, characterized in that the transformer for grounding the neutral is mounted on a withdrawable element, eliminating the need for lifting mechanisms when it is built into the cabinet or removed from the cabinet.