Conversion protection device applied to transformer and three-phase autotransformer cabinet

Abstract

The utility model discloses a conversion protection device applied to a transformer and a three-phase autotransformer cabinet. The device comprises a circuit breaker QF1, a soft start safety assembly, an autotransformer T1 and a secondary power supply assembly, wherein the soft start safety assembly comprises a time relay KM1, a time relay KM2, a resistor Ra, a resistor Rb and a resistor Rc; the U phase, the V phase and the W phase of the circuit breaker QF1 are respectively connected with the A phase, the B phase and the C phase of a time relay KM1; the U phase, the V phase and the W phase of the full relay KM2 are respectively connected with resistors Ra, Rb and Rc and then are connected with the time relay KM1 in parallel; the U phase, the V phase and the W phase of the time relay KM1 are respectively connected with the A phase, the B phase and the C phase of the autotransformer T1; the secondary power supply assembly is connected with the U phase and the V phase of the circuit breaker QF1. According to the utility model, the time relay KM2 is connected in series with the resistor and then is connected in parallel with the time relay KM1 serving as a main power switch, and the contact of the time relay KM1 is delayed to be closed, so that the purpose of suppressing peak surge is achieved, and the main power switch device is protected.

Description

Technical Field

[0001] This utility model relates to the field of transformer technology, specifically to a switching protection device for transformers and a three-phase autotransformer cabinet. Background Technology

[0002] In the use of high-power test power supplies and large power electronic equipment, the grid voltage often exceeds the national grid standard of 380V. In such cases, the non-standard 480V / 690V voltage on the AC connection side of the equipment needs to be converted to the desired 380V voltage using a three-phase autotransformer. Currently, relying solely on a three-phase transformer to convert the voltage to the equipment's operating voltage results in significant spikes in current and voltage upon initial power-on, potentially damaging or burning out the AC-side switching devices. Utility Model Content

[0003] The technical problem to be solved by this utility model is to address the issue of large peak current and voltage during the first use of a non-standard high-voltage transformer after conversion.

[0004] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0005] A switching protection device for a transformer includes: a circuit breaker QF1, a soft-start safety component, an autotransformer T1, and a secondary power supply component; wherein the soft-start safety component includes time relays KM1 and KM2, and resistors Ra, Rb, and Rc;

[0006] The U, V, and W phases of circuit breaker QF1 are connected to the A, B, and C phases of time relay KM1, respectively; the U, V, and W phases of full relay KM2 are connected to resistors Ra, Rb, and Rc, respectively, and then connected in parallel with time relay KM1; the U, V, and W phases of time relay KM1 are connected to the A, B, and C phases of autotransformer T1, respectively; the secondary power supply assembly is connected to the U and V phases of circuit breaker QF1.

[0007] In one embodiment of this utility model, phases A, B and C of circuit breaker QF1 are connected to the primary side of transformer.

[0008] In one embodiment of this utility model, the U-phase, V-phase, and W-phase of the autotransformer T1 are connected to the secondary side of the transformer.

[0009] In one embodiment of this utility model, the secondary power supply component includes a single-phase isolation transformer T2, a micro-circuit breaker QF2, and a switching power supply DS1; the U phase and V phase of the circuit breaker QF1 are respectively connected to the N-line terminal and L-line terminal of the input side of the single-phase isolation transformer T2; the output side of the single-phase isolation transformer T2 is connected to one end of the micro-circuit breaker QF2, and the other end of the micro-circuit breaker QF2 is connected to the switching power supply DS1.

[0010] In one embodiment of this utility model, N-line and L-line terminals are led out on the circuit between the micro-circuit breaker QF2 and the switching power supply DS1.

[0011] In one embodiment of this utility model, the secondary power supply component includes multiple magnetic rings, which are respectively disposed between the single-phase isolation transformer T2 and the micro-circuit breaker QF2, and between the micro-circuit breaker QF2 and the switching power supply DS1.

[0012] This utility model also provides a three-phase autotransformer cabinet, including the aforementioned switching protection device applied to transformers.

[0013] Compared with the prior art, the beneficial effect of this utility model is that the time relay KM2 is connected in series with a resistor and then connected in parallel with the time relay KM1, which is the main power switch, to delay the closing of the contacts of the time relay KM1, thereby suppressing the surge and protecting the main power switching device. Attached Figure Description

[0014] Figure 1 The circuit of this utility model is intended to be a switching protection device applied to a transformer.

[0015] Figure 2 This is a schematic diagram of a circuit breaker according to an embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of the soft boot security component according to an embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram of an autotransformer according to an embodiment of the present invention.

[0018] Figure 5 This is a schematic diagram of the secondary power supply component according to an embodiment of the present utility model. Detailed Implementation

[0019] To facilitate understanding of the technical solution of this utility model by those skilled in the art, the technical solution of this utility model will now be further described in conjunction with the accompanying drawings.

[0020] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0021] Please see Figures 1 to 5As shown, this utility model provides a switching protection device for transformers, including: a circuit breaker QF1, a soft-start safety component, an autotransformer T1, and a secondary power supply component. The soft-start safety component includes time relays KM1 and KM2, and resistors Ra, Rb, and Rc.

[0022] The U, V, and W phases of circuit breaker QF1 are connected to the A, B, and C phases of time relay KM1, respectively. The U, V, and W phases of full relay KM2 are connected to resistors Ra, Rb, and Rc, respectively, and then connected in parallel with time relay KM1. The U, V, and W phases of time relay KM1 are connected to the A, B, and C phases of autotransformer T1, respectively, and the secondary power supply components are connected to the U and V phases of circuit breaker QF1.

[0023] In one embodiment of this utility model, phases A, B, and C of circuit breaker QF1 are connected to the primary side of transformer to detect AC phase loss. Phases U, V, and W of autotransformer T1 are connected to the secondary side of transformer for over-temperature protection.

[0024] In one embodiment of this utility model, the secondary power supply component can supply power to the electrical components in a three-phase autotransformer cabinet. Specifically, the secondary power supply component includes a single-phase isolation transformer T2, a miniature circuit breaker QF2, a switching power supply DS1, and multiple magnetic rings. The U-phase and V-phase of the circuit breaker QF1 are connected to the N-line and L-line terminals of the input side of the single-phase isolation transformer T2, respectively. The output side of the single-phase isolation transformer T2 is connected to one end of the miniature circuit breaker QF2, and the other end of the miniature circuit breaker QF2 is connected to the switching power supply DS1. The switching power supply DS1 converts the AC 220V voltage to 24V voltage, which can power the three-color indicator lights in the three-phase autotransformer cabinet, allowing for a direct visual assessment of the operating status. N-line and L-line terminals are led out from the circuit between the miniature circuit breaker QF2 and the switching power supply DS1, through which contactors in the three-phase autotransformer cabinet can be connected.

[0025] In one embodiment of this invention, during use, pressing the start button of time relay KM2 causes its contacts to close. Current flows through resistors Ra, Rb, and Rc for current limiting and buffering before entering the autotransformer T1 and flowing into the load. After a period of time, such as 5 seconds, the contacts of time relay KM2 open, while the contacts of time relay KM1 close. Current then flows through time relay KM1 and through the autotransformer T1 before flowing into the load. This invention uses a series resistor between time relay KM2 and time relay KM1 (which acts as the main power switch) to delay the closing of time relay KM1's contacts, thereby suppressing surge currents and protecting the main power switching device.

[0026] In another embodiment of this utility model, a three-phase autotransformer cabinet is also provided, including the aforementioned switching protection device for transformers. The three-phase autotransformer cabinet is equipped with an emergency stop button. When the equipment is in the start-up state, pressing the emergency stop button disconnects the main contactor in the equipment. When the start button of time relay KM2 is in the closed state and the emergency stop button is turned, the equipment will cycle through soft-start operations. That is, time relay KM2 first performs current limiting buffering, delaying the contact closing time of time relay KM1. After time relay KM1 has worked for a period of time, the contact opens again, and time relay KM2 performs delayed soft-start again, in a cycle.

[0027] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0028] The above-described embodiments are merely examples of implementation methods of the utility model. The scope of protection of this utility model is not limited to the above-described embodiments. For those skilled in the art, several modifications and improvements can be made without departing from the concept of this utility model, and these all fall within the scope of protection of this utility model.

Claims

1. A switching protection device applied to a transformer, characterized in that, include: Circuit breaker QF1, soft start safety component, autotransformer T1 and secondary power supply component; wherein, the soft start safety component includes time relays KM1 and KM2, resistors Ra, Rb and Rc; The U, V, and W phases of circuit breaker QF1 are connected to the A, B, and C phases of time relay KM1, respectively; the U, V, and W phases of full relay KM2 are connected to resistors Ra, Rb, and Rc, respectively, and then connected in parallel with time relay KM1; the U, V, and W phases of time relay KM1 are connected to the A, B, and C phases of autotransformer T1, respectively; the secondary power supply assembly is connected to the U and V phases of circuit breaker QF1.

2. The switching protection device for transformers according to claim 1, characterized in that, Phases A, B, and C of circuit breaker QF1 are connected to the primary side of the transformer.

3. The switching protection device for transformers according to claim 1, characterized in that, The U-phase, V-phase, and W-phase of the autotransformer T1 are connected to the secondary side of the transformer.

4. The switching protection device for transformers according to claim 1, characterized in that, The secondary power supply components include a single-phase isolation transformer T2, a micro-circuit breaker QF2, and a switching power supply DS1; the U-phase and V-phase of the circuit breaker QF1 are connected to the N-line and L-line of the input side of the single-phase isolation transformer T2, respectively; the output side of the single-phase isolation transformer T2 is connected to one end of the micro-circuit breaker QF2, and the other end of the micro-circuit breaker QF2 is connected to the switching power supply DS1.

5. The switching protection device for transformers according to claim 4, characterized in that, On the circuit between the micro circuit breaker QF2 and the switching power supply DS1, lead out the N and L line terminals.

6. The switching protection device for transformers according to claim 4, characterized in that, The secondary power supply assembly includes multiple magnetic rings, which are respectively installed between the single-phase isolation transformer T2 and the micro-circuit breaker QF2, and between the micro-circuit breaker QF2 and the switching power supply DS1.

7. A three-phase autotransformer cabinet, characterized in that, Includes the switching protection device applied to a transformer as described in any one of claims 1-6.

Images