Circuit device for reducing excitation current at starting moment of transformer
By connecting the resistor and normally closed temperature protection switches in series in the coil winding on the input side of the transformer, and combining them with the normally open contacts of the contactor or relay, the circuit breaker trip and fuse fuse problems caused by excessive excitation current at the moment of the transformer start-up is solved, and the normal operation of the transformer is achieved.
Patent Information
- Application Number
- CN202422575040.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-23
- Publication Date
- 2025-08-29
- Estimated Expiration
- 2034-10-23
AI Technical Summary
The excitation current is too high at the moment of starting the transformer, causing the circuit breaker to automatically trip or the fuse to fuse, resulting in poor operation and damage to the components.
The resistor and normally closed temperature protection switch are connected in series in the coil winding on the input side of the transformer, and are used in combination with the normally open contacts of the contactor or relay. The excitation current is reduced by the resistance, and the normally closed temperature protection switch is used for component protection.
Effectively reduce the excitation current at the moment of starting the transformer, avoid circuit breaker tripping and fuse fuse blowing, and ensure the normal operation of the transformer.
Smart Images
Figure CN223284832U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of transformers, and in particular relates to a circuit device for reducing the instantaneous excitation current of a transformer at startup. Background Art
[0002] The transformer is mainly composed of input side coil winding, output side coil winding and iron core. At the moment of power-on startup, a large excitation current will be generated on the input side of the transformer.
[0003] Typically, a circuit breaker with a short-circuit protection function is used on the input side of the transformer as a switching device for powering on and off the transformer, or a fuse with a short-circuit protection function is installed on the input side of the transformer as a protection element for the line.
[0004] However, if the excitation current generated at the moment of transformer startup is too large and exceeds the instantaneous tripping current value of the circuit breaker, the circuit breaker will automatically trip and the switch will not be closed; or if it exceeds the melting current value of the fuse, the fuse will melt instantaneously, which will cause the user to have an unsmooth operation when starting the transformer or unnecessary damage to the fuse core component, thereby causing user dissatisfaction.
[0005] Therefore, it is necessary to design a circuit device that can reduce the excitation current of the transformer at the moment of startup, and will not cause the circuit breaker to trip instantaneously or the fuse in the line to melt instantaneously when closing the circuit, so that the circuit breaker switch or protective fuse can work normally when the transformer is energized and closed. Summary of the Invention
[0006] The utility model mainly solves the technical problems existing in the above-mentioned prior art and provides a circuit device for reducing the instantaneous excitation current of a transformer when it is started.
[0007] The above-mentioned technical problems of the present utility model are mainly solved by the following technical solutions: a circuit device for reducing the instantaneous excitation current of a transformer at startup, comprising an input side coil winding and an output side coil winding of the transformer, wherein the normally open contact of a contactor or a relay is connected in series to the neutral line L in the input side coil winding, a resistor and a normally closed temperature protection switch are connected in series and connected to both ends of the normally open contact of the contactor or the relay, a working voltage tap is provided on the input side coil winding, the coil of the contactor or the relay is connected in series between the working voltage tap and the normally open contact of the contactor or the relay, and the working voltage tap provides working voltage for the coil of the contactor or the relay.
[0008] Preferably, the normally closed temperature protection switch is bundled and fixed on the outside of the resistor.
[0009] The working principle of the present utility model is as follows: at the moment of transformer startup, before the normally open contacts of the contactor or relay are closed, the neutral wire L in the input-side coil winding forms a loop through a resistor and a normally closed temperature protection switch. The resistor reduces the excitation current on the transformer input side at the moment of startup, and the normally closed temperature protection switch, which is bundled and fixed to the outside of the resistor, protects the transformer. After the coil of the contactor or relay is energized to close its normally open contacts, the neutral wire L in the input-side coil winding forms a loop through the normally open contacts of the contactor or relay, while the resistor and the normally closed temperature protection switch are short-circuited, and the transformer enters normal operating mode. After the transformer is shut down, the coil of the contactor or relay loses power, its normally open contacts reset, and the neutral wire L in the input-side coil winding forms a loop through the resistor and the normally closed temperature protection switch, waiting for the next startup of the transformer to repeat the above process.
[0010] This utility model improves the input side of the existing transformer by adding a resistor, a normally closed temperature protection switch, and a contactor or relay. This reduces the excitation current on the transformer input side at the moment of startup, preventing the circuit breaker from tripping or the fuse in the line from melting when the switch is closed. This allows the circuit breaker switch or protective fuse to operate normally when the transformer is powered on and closed. Therefore, this utility model has the advantages of simple structure and reasonable design. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 It is a structural schematic diagram of the present utility model.
[0012] In the figure, 1-resistor, 2-normally closed temperature protection switch, 3-normally open contact of contactor or relay, 4-coil of contactor or relay, 5-input side coil winding, 6-output side coil winding, 7-working voltage tap. DETAILED DESCRIPTION
[0013] The technical solution of the present invention will be further specifically described below with reference to embodiments and in conjunction with the accompanying drawings.
[0014] Example: See Figure 1 The utility model includes a transformer input-side coil winding and an output-side coil winding. A normally open contact of a contactor or relay is connected in series to the neutral line L in the input-side coil winding. A resistor and a normally closed temperature protection switch are connected in series and connected to both ends of the normally open contact of the contactor or relay. A working voltage tap is provided on the input-side coil winding. The coil of the contactor or relay is connected in series between the working voltage tap and the normally open contact of the contactor or relay, and the working voltage tap provides the working voltage to the coil of the contactor or relay. The normally closed temperature protection switch is bundled and fixed to the outside of the resistor.
[0015] The working principle of the present utility model is as follows: at the moment of transformer startup, before the normally open contacts of the contactor or relay are closed, the neutral wire L in the input-side coil winding forms a loop through a resistor and a normally closed temperature protection switch. The resistor reduces the excitation current on the transformer input side at the moment of startup, and the normally closed temperature protection switch, which is bundled and fixed to the outside of the resistor, protects the transformer. After the coil of the contactor or relay is energized to close its normally open contacts, the neutral wire L in the input-side coil winding forms a loop through the normally open contacts of the contactor or relay, while the resistor and the normally closed temperature protection switch are short-circuited, and the transformer enters normal operating mode. After the transformer is shut down, the coil of the contactor or relay loses power, its normally open contacts reset, and the neutral wire L in the input-side coil winding forms a loop through the resistor and the normally closed temperature protection switch, waiting for the next startup of the transformer to repeat the above process.
[0016] This utility model improves the input side of the existing transformer by adding a resistor, a normally closed temperature protection switch, and a contactor or relay. This reduces the excitation current on the transformer input side at the moment of startup, preventing the circuit breaker from tripping or the fuse in the line from melting when the switch is closed. This allows the circuit breaker switch or protective fuse to operate normally when the transformer is powered on and closed. Therefore, this utility model has the advantages of simple structure and reasonable design.
[0017] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and is susceptible to numerous variations. Any simple modifications, equivalent variations, and modifications to the above embodiments based on the technical essence of the present invention shall be deemed to fall within the scope of protection of the present invention.
Claims
1. A circuit device for reducing the instantaneous excitation current of a transformer at startup, comprising a transformer input side coil winding and an output side coil winding, characterized in that The neutral line L in the input side coil winding is connected in series with the normally open contact of the contactor or relay, and the resistor and the normally closed temperature protection switch are connected in series and connected to the two ends of the normally open contact of the contactor or relay. A working voltage tap is provided on the input side coil winding, and the coil of the contactor or relay is connected in series between the working voltage tap and the normally open contact of the contactor or relay, and the working voltage tap provides the working voltage for the coil of the contactor or relay.
2. A circuit device for reducing the instantaneous excitation current of a transformer when starting according to claim 1, characterized in that The normally closed temperature protection switch is bound and fixed on the outside of the resistor.