CN209860589U - Device for eliminating excitation surge current - Google Patents
Device for eliminating excitation surge current Download PDFInfo
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- CN209860589U CN209860589U CN201920723484.0U CN201920723484U CN209860589U CN 209860589 U CN209860589 U CN 209860589U CN 201920723484 U CN201920723484 U CN 201920723484U CN 209860589 U CN209860589 U CN 209860589U
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Abstract
The utility model relates to a device for eliminating excitation surge current, which is suitable for inhibiting the excitation surge current generated when a power supply is connected into a transformer, and comprises a primary main circuit and a secondary control circuit which are formed by combining a transformer protection switch element, a current limiting element, a time delay switch element and a magnetizing switch element, wherein the primary main circuit is connected with the secondary control circuit in parallel; in the primary main circuit, one end of a main contact of a transformer protection switching element is connected with a power supply, and the other end of the main contact of the transformer protection switching element is connected with the primary side of a transformer; one end of a main contact of the magnetizing switch element is connected with a power supply, and the other end of the main contact of the magnetizing switch element is connected with the primary side of the transformer after being connected with the current limiting element in series; one end of the secondary control circuit is connected with the power supply, and the other end of the secondary control circuit is connected with the neutral line; the secondary control circuit is used for controlling the on-off of each element in the primary main circuit. The device is small in size, simple and easy to install and connect, and can stably and safely connect a power supply to the primary side of the transformer so as to realize a power supply function. In the access process, high excitation current impact cannot be generated to damage all components.
Description
Technical Field
The utility model relates to an electrical control field, concretely relates to eliminate device of excitation inrush current.
Background
The power supply output by power supply equipment such as a diesel generating car is a 0.4kV low-voltage power supply, but when a user needs a 10kV power supply, the 0.4kV power supply needs to be boosted to the 10kV power supply. However, when a 0.4kV power supply is transmitted to the low-voltage side of the step-up transformer, a rated current of 20-30 times of the maximum rated current of the low-voltage side of the transformer is generated (for example, when a 500kW diesel generator has a rated current of 721A, and a 0.4kV power supply is directly connected to the step-up transformer, an excitation inrush current of 27280a is generated at the low-voltage side of the 630kVA step-up transformer, and at this time, a protection switch of the step-up transformer is tripped or the diesel generator is directly damaged. Aiming at the situation that a boosting transformer with a larger switching-in low-voltage power supply generates higher magnetizing inrush current, the method generally captures a phase angle when a three-phase power supply is switched off and then switches on at a proper time and utilizes the bias magnetism to offset the remanence in China, has high requirement on time precision, is complex to operate, has higher cost and is not beneficial to actual operation. In the occasion with low requirement on time precision, the switching-on and boosting variable protection switch is tried for many times according to the working experience of an operator so as to be switched on, and the time consumption of the operation process is long.
SUMMERY OF THE UTILITY MODEL
The utility model discloses to the technical problem who exists among the prior art, a eliminate device that excites inrush current is provided, before combined floodgate transformer protection switch, magnetize for the transformer through this device in advance, after magnetizing several seconds, transformer instantaneous electromagnetic field intensity will reach about 80% of the rated electromagnetic field of transformer, eliminate the device output control signal combined floodgate transformer protection switch that excites inrush current this moment, thereby reach the purpose that reduces, eliminates transformer excitation inrush current, make the power insert the transformer smoothly.
The utility model provides an above-mentioned technical problem's technical scheme as follows:
a device for eliminating excitation inrush current is suitable for inhibiting the excitation inrush current generated when a power supply is connected into a transformer, is arranged between the power supply and the transformer, and comprises a primary main circuit and a secondary control circuit which are formed by combining a transformer protection switching element, a current limiting element, a time delay switching element and a magnetizing switching element, wherein the primary main circuit is connected with the secondary control circuit in parallel; in the primary main circuit, one end of a main contact of the transformer protection switching element is connected with the power supply, and the other end of the main contact of the transformer protection switching element is connected with the primary side of the transformer; one end of a main contact of the magnetizing switch element is connected with the power supply, and the other end of the main contact of the magnetizing switch element is connected with the primary side of the transformer after being connected with the current limiting element in series; one end of the secondary control circuit is connected with the power supply, and the other end of the secondary control circuit is connected with the neutral line; the secondary control circuit comprises a magnetizing switch element control circuit, a time control circuit, a transformer protection switch element closing control circuit and a transformer protection switch element opening control circuit which are respectively connected in parallel; the magnetizing switch element control circuit controls the magnetizing switch element and the time control circuit to be switched on and off; the time control circuit controls the on-off of the switching-on control circuit of the transformer protection switching element; the transformer protection switching element switching-on control circuit controls the switching-on of the transformer protection switching element; the transformer protection switching element opening control circuit controls the opening of the transformer protection switching element.
The power supply is connected to the transformer when the transformer protection switching element is switched on, and the power supply is disconnected when the transformer protection switching element is switched off; when the magnetizing switch element is closed, the power supply, the control coil of the time delay switch element and the current limiting element are connected with the transformer; the secondary control circuit is used for controlling the on-off of the magnetizing switch element, the magnetizing switch element and the transformer protection switch element form linkage control, the magnetizing switch element controls the main contact of the transformer protection switch element to be switched on, and the time delay switch element delays the switching-on time of the main contact of the transformer protection switch element; the magnetizing switch element is turned off when the transformer protection switch element main contact is turned on.
Before the transformer protection switch is switched on, the magnetizing switch is closed firstly, the magnetizing switch is connected with a coil of the time delay switch element in series, the boosting transformer is magnetized in advance, after the magnetizing time is several seconds, the instantaneous electromagnetic field intensity of the transformer reaches about 80% of the rated electromagnetic field of the transformer, and the time delay switch element outputs a signal to switch on the transformer protection switch, so that the purpose of reducing and eliminating the excitation inrush current of the transformer is achieved, and a power supply is connected to the transformer smoothly.
Preferably, the magnetizing switch element control circuit includes a closing button, a first normally closed auxiliary contact of the transformer protection switch element, and a control coil of the magnetizing switch element, which are connected in sequence, the closing button is connected to the power supply, and the control coil of the magnetizing switch element is connected to the neutral line. When the closing button is pressed, the magnetizing switch element control circuit is switched on, a control coil of the magnetizing switch element is electrified to control the normally open contact of the magnetizing switch element to be closed, the main contact of the magnetizing switch element in the primary main circuit is closed, and the current limiting element is put into operation to pre-magnetize the transformer; meanwhile, the current limiting element limits the current, so that a small current is provided for a path, the transformer generates a counter potential, and the magnetizing inrush current of the transformer protection switching element during switching-on is inhibited.
Preferably, two ends of the closing button are connected in parallel with the first normally open auxiliary contact of the magnetizing switch element. The first normally open auxiliary contact of the magnetizing switch element and the control coil of the magnetizing switch element form self-locking, when the control coil of the magnetizing switch element is electrified, the first normally open auxiliary contact of the magnetizing switch element is closed, and when the closing button is disconnected, the control coil of the magnetizing switch element is still in a path, so that the main contact of the magnetizing switch element is still in a closed state, and the transformer is in a pre-magnetizing state.
Preferably, the time control circuit comprises a second normally open auxiliary contact of the magnetizing switch element and a control coil of the time delay switch element which are connected in series, and the time control circuit is connected in parallel at two ends of the control coil of the magnetizing switch element. When the control coil of the magnetizing switch element is electrified, the second normally-open auxiliary contact of the magnetizing switch element is closed, the control coil of the time delay switch element is electrified, and the normally-open contact of the time delay switch element is controlled to be closed after time delay. The utility model discloses in, the time of time delay is the time of pre-magnetizing promptly. The second normally open auxiliary contact of the magnetizing switch element is connected in series with the control coil of the time delay switch element, so that the magnetizing switch element can be ensured to be switched on before the time delay switch element, and the transformer protection switch element is prevented from being switched on in advance under the condition of no magnetizing.
Preferably, the transformer protection switching element closing control circuit includes a time delay switching element normally open contact, a transformer protection switching element closing coil, and a transformer protection switching element second normally closed auxiliary contact, which are connected in series in sequence, the time delay switching element normally open contact is connected to the power supply, and the transformer protection switching element second normally closed auxiliary contact is connected to the neutral line. When the normally open contact of the time delay switch element is closed, the closing coil of the transformer protection switch element is electrified, the normally open main contact of the transformer protection switch element is closed, the normally open auxiliary contact of the transformer protection switch element is closed, the normally closed auxiliary contact of the transformer protection switch element is opened, the first normally closed auxiliary contact of the transformer protection switch element is opened, the main contact of the magnetizing switch element is opened, the control circuit of the magnetizing switch element is opened, and pre-magnetizing is finished.
Preferably, the transformer protection switch element opening control circuit comprises an opening button, a transformer protection switch element opening coil and a transformer protection switch element third normally open auxiliary contact which are sequentially connected in series, the opening button is connected with the power supply, and the transformer protection switch element third normally open auxiliary contact is connected with the neutral line. When the transformer is used and the power supply needs to be disconnected, the opening button is pressed, the opening coil of the transformer protection switch element is electrified, meanwhile, the normally open contact of the transformer protection switch element is disconnected, the normally closed contact is closed, the normally open main contact of the transformer protection switch element is disconnected, and the transformer disconnects the power supply.
Preferably, two ends of the opening button are connected in parallel with a temperature control switch, and the temperature control switch is normally opened. When the temperature of the transformer protection switch element is too high and exceeds the temperature threshold of the transformer protection switch element in the use process of the transformer, in order to prevent the danger of overheating, fire and the like, the temperature control switch is closed, the opening coil of the transformer protection switch element is electrified, the normally open contact of the transformer protection switch element is opened, the normally closed contact is closed, the transformer disconnects the power supply, and the same function as that of pressing the opening button is completed.
Preferably, the time delay switch element is a time relay, and the time delay closing time of a normally open contact of the time relay is 3-5 seconds. Within a few seconds of time delay, a small current is provided for the transformer, so that the transformer generates a counter potential in advance, and the magnetizing inrush current when the transformer protection switching element is switched on is effectively reduced.
Preferably, a current fuse is further connected in series in the secondary control circuit, one end of the current fuse is connected to the power supply, and the other end of the current fuse is connected to the input end of the secondary control circuit. The current fuse is arranged, when the current is overlarge due to abnormal conditions such as short circuit in the control circuit, the current fuse is fused, and the damage of the high current to components in the secondary control circuit is prevented.
Preferably, the primary main circuit is further provided with a magnetizing line protection switching element, and the magnetizing line protection switching element is arranged between the transformer protection switching element and the magnetizing switching element; the magnetizing circuit protection switch element is normally open, one end of a normally open main contact of the magnetizing circuit protection switch element is connected with the main contact of the transformer protection switch element, and the other end of the normally open main contact of the magnetizing circuit protection switch element is connected with the main contact of the magnetizing switch element.
The utility model has the advantages that: the device is small in size, simple and easy to install and connect, and can stably, safely and smoothly connect a power supply (such as a diesel generator power supply) to the primary side of the transformer so as to realize a power supply function. The device magnetizes the transformer in advance, after magnetizing for several seconds, the instantaneous electromagnetic field intensity of the transformer reaches about 80% of the rated electromagnetic field of the transformer, and the device for eliminating the magnetizing inrush current outputs a control signal to close a transformer protection switch, so that the purpose of reducing and eliminating the magnetizing inrush current of the transformer is achieved, and a power supply is smoothly connected to the transformer. In the access process, high exciting current can not be generated to impact the protection switch element and the transformer of the boosting transformer, and the damage of the power supply, the transformer and the protection switch element of the transformer caused by overhigh current can not be caused.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
In the drawings, the components represented by the respective reference numerals are listed below:
KM, a magnetizing switch element, QF, a transformer protection switch element, QF1, a magnetizing circuit protection switch element, KT, a delay switch element, R1-R3, a current limiting element, FU, a current fuse, SB1, a closing button, SB2, a separating button, M, an energy storage motor, X, a closing coil of the transformer protection switch element, F, a separating coil of the transformer protection switch element, HR, a closing indicator lamp, HG, a separating indicator lamp, HY, a fault indicator lamp, HW and a magnetizing completion indicator lamp,
1. the transformer protection switch element comprises a magnetizing switch element main contact, 101, a magnetizing switch element first normally open auxiliary contact, 102, a magnetizing switch element second normally open auxiliary contact, 2, a transformer protection switch element main contact, 201, a transformer protection switch element first normally closed auxiliary contact, 202, a transformer protection switch element second normally closed auxiliary contact, 203, a transformer protection switch element third normally open auxiliary contact, 204, a transformer protection switch element fourth normally closed contact, 205, a transformer protection switch element fifth normally open auxiliary contact, 206, a transformer protection switch element sixth normally closed auxiliary contact, 207 and a transformer protection switch element alarm contact.
Detailed Description
The principles and features of the present invention are described below in conjunction with the following drawings, the examples given are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.
As shown in fig. 1, the device for eliminating the magnetizing inrush current is suitable for suppressing the magnetizing inrush current generated when a power supply is connected to a transformer, and particularly suitable for suppressing the magnetizing inrush current generated when a three-phase power supply is connected to a transformer having a Dyn11 configuration. The application scenario of the embodiment is to connect a 400V low-voltage power supply of the diesel generating car into a 10kV high-voltage power grid. The device is arranged between a low-voltage power supply and a booster transformer, and comprises a primary main circuit and a secondary control circuit which are formed by combining a transformer protection switching element QF, a current limiting element (R1, R2 and R3), a time delay switching element KT and a magnetizing switching element KM, wherein the primary main circuit is connected with the secondary control circuit in parallel. In the embodiment, the transformer protection switching element QF is a frame-type circuit breaker, and is provided with three pairs of linked normally open main contacts, a plurality of normally open auxiliary contacts, a plurality of normally closed auxiliary contacts, a closing coil X, an opening coil F and an energy storage motor M for driving the transformer protection switching element QF to perform closing and opening actions; the switching-on/switching-off device is also provided with a switching-on button SB1 and a switching-off button SB2 which are respectively used for controlling the switching-on coil X and the switching-off coil F to be electrified; the intelligent protection switch is also provided with a normally open alarm contact, when normal switching-off and switching-on are carried out, the alarm contact does not act, and when the transformer protection switch element QF has a fault, the alarm contact is closed. The current limiting elements (R1, R2, R3) may be adjustable resistors, or fixed resistors with suitable resistance values calculated according to actual needs may be used, and three fixed resistors of 6 Ω are used in this embodiment. In this embodiment, the delay switch element KT is controlled in a delayed manner using a time relay including a control coil and at least two pairs of normally open contacts. The magnetizing switch element KM uses a relay with a control coil, three linked normally open main contacts and at least two normally open auxiliary contacts.
In the primary main circuit, one end of a transformer protection switching element QF main contact 2 is connected with a 400V three-phase power supply, and the other end of the transformer protection switching element QF main contact is connected with a primary side winding joint of a transformer; one end of a main contact 1 of the magnetizing switch element KM is connected with a three-phase power supply, and the other end of the main contact is respectively connected with a primary side winding joint of a transformer after being connected with a current limiting element (R1/R2/R3) in series; the secondary control circuit is a single-phase circuit, one end of the secondary control circuit is connected with any phase of the three-phase power supply, and the other end of the secondary control circuit is connected with the neutral line; the primary side winding of the transformer with the Dyn11 structure is connected in a Y shape, the short-circuit point of the winding is a neutral point, the lead-out line of the neutral point is a neutral line, the neutral line is grounded, and one end of the current output of the secondary control circuit is connected with the neutral point. The secondary control circuit comprises a magnetizing switch element control circuit, a time control circuit, a transformer protection switch element closing control circuit and a transformer protection switch element opening control circuit which are respectively connected in parallel; the magnetizing switch element control circuit controls the main contact 1 of the magnetizing switch element KM and the time control circuit to be switched on and off; the time control circuit controls the on-off of a switching-on control circuit of the transformer protection switching element; the transformer protection switching element switching-on control circuit controls the transformer protection switching element QF to switch on, and when the transformer protection switching element QF is switched on, the normally open contact of the transformer protection switching element QF is closed and the normally closed contact of the transformer protection switching element QF is opened; the transformer protection switching element opening control circuit controls the transformer protection switching element QF to open, and during opening, the normally open contact of the transformer protection switching element QF is opened and the normally closed contact of the transformer protection switching element QF is closed.
The transformer protection switching element QF is switched on to connect the power supply to the transformer, and the switching-off of the transformer is to disconnect the power supply; when the magnetizing switch element KM is closed, a power supply, a control coil of the time delay switch element KT, and current limiting elements (R1, R2 and R3) are connected with the transformer; the secondary control circuit is used for controlling the on-off of the magnetizing switch element KM, the magnetizing switch element KM and the transformer protection switch element QF form linkage control, the magnetizing switch element KM controls the on-off of the main contact 2 of the transformer protection switch element QF, and the delay switch element KT delays the on-off time of the main contact 2 of the transformer protection switch element QF; the magnetizing switch element KM is turned off when the transformer protection switch element QF main contact 2 is turned on.
Before a transformer protection switching element QF is switched on, a magnetizing switching element KM is closed, the magnetizing switching element KM is connected with a control coil of a time delay switching element KT in series, a boosting transformer is magnetized in advance, a test shows that after the time of magnetizing is about 3 seconds, the instantaneous electromagnetic field intensity of the transformer reaches about 80% of the rated electromagnetic field of the transformer, the time delay switching element KT outputs a signal to switch on the transformer protection switching element QF, a main contact 2 of the transformer protection switching element QF is closed, and therefore the purpose of reducing and eliminating transformer excitation inrush current is achieved, and a power supply is enabled to be smoothly connected into the transformer.
In this embodiment, the magnetizing switch element control circuit includes a closing button SB1, a first normally closed auxiliary contact 201 of the transformer protection switch element, and a control coil of the magnetizing switch element KM, which are connected in sequence, the closing button SB1 is connected to the power supply, and the control coil of the magnetizing switch element KM is connected to the neutral line. When a closing button SB1 is pressed, a control circuit of a magnetizing switch element KM is switched on, a control coil of the magnetizing switch element KM is electrified, a normally open contact of the magnetizing switch element KM is controlled to be closed, a main contact 1 of the magnetizing switch element KM in a primary main circuit is closed, and current limiting elements (R1, R2 and R3) are put into operation to pre-magnetize a transformer; meanwhile, the current limiting elements (R1, R2 and R3) limit the current, so that the current with smaller current relative to the rated current is provided for the access, the transformer generates a counter potential to generate an electromagnetic field, the purpose of pre-magnetizing the transformer is achieved, and the magnetizing inrush current when the transformer protection switching element is switched on is suppressed.
In this embodiment, the two ends of the closing button SB1 are connected in parallel with the first normally open auxiliary contact 101 of the magnetizing switch element KM. The first normally open auxiliary contact 101 of the magnetizing switch element KM and the control coil of the magnetizing switch element KM form self-locking, when the control coil of the magnetizing switch element KM is electrified, the first normally open auxiliary contact 101 of the magnetizing switch element KM is closed, and when the switch-on button SB1 is disconnected, the control coil of the magnetizing switch element KM is still in a closed state, so that the main contact 1 of the magnetizing switch element KM is still in a closed state, and the transformer is still in a pre-magnetizing state.
In this embodiment, the time control circuit includes the second normally open auxiliary contact 102 of the magnetizing switch element KM and the control coil of the delay switch element KT connected in series, and the time control circuit is connected in parallel to both ends of the control coil of the magnetizing switch element KM. When the control coil of the magnetizing switch element KM is energized, the second normally-open auxiliary contact 102 of the magnetizing switch element KM is closed, the control coil of the delay switch element KT is energized, and the normally-open contact of the delay switch element KT is controlled to be closed after a preset delay time. The utility model discloses in, the time of time delay is the time of pre-magnetizing promptly. The second normally open auxiliary contact 102 of the magnetizing switch element KM is connected in series with the control coil of the delay switch element KT, so that the magnetizing switch element KM is connected before the delay switch element KT, and the transformer protection switch element is prevented from being connected in advance under the condition of non-magnetizing.
In this embodiment, the switch-on control circuit of the transformer protection switching element includes a time-delay switching element KT normally-open contact, a transformer protection switching element QF switch-on coil X, and a transformer protection switching element second normally-closed auxiliary contact 202, which are sequentially connected in series, the time-delay switching element KT normally-open contact is connected to the power supply, and the transformer protection switching element second normally-closed auxiliary contact 202 is connected to the neutral line. When the KT normally-open contact of the time-delay switch element is closed, the switch-on coil of the transformer protection switch element QF is electrified, the normally-open main contact 2 of the transformer protection switch element QF is closed, and meanwhile, the normally-open auxiliary contact of the transformer protection switch element QF is closed and the normally-closed auxiliary contact is opened. When the first normally closed auxiliary contact 201 of the transformer protection switching element is disconnected, the main contact 1 of the magnetizing switching element KM is disconnected, and the control circuit of the magnetizing switching element is disconnected, that is, pre-magnetizing is finished.
And a closing indicator lamp HR is further arranged in the secondary control circuit, and is connected in parallel with the transformer protection switching element closing control circuit after being connected in series with the fifth normally-opened auxiliary contact 205 of the transformer protection switching element. When the transformer protection switching element QF is switched on, the switching-on indicator lamp HR lights the red lamp.
In this embodiment, the transformer protection switching element opening control circuit includes an opening button SB2, a transformer protection switching element QF opening coil F, and a transformer protection switching element third normally open auxiliary contact 203, which are connected in series in sequence; the opening button SB2 is connected to the power supply, and the third normally open auxiliary contact 203 of the transformer protection switching element is connected to the neutral line. When the transformer is used and the power supply needs to be disconnected, the opening button SB2 is pressed, the opening coil F of the transformer protection switch element QF is electrified, the normally open contact of the transformer protection switch element QF is opened, the normally closed contact is closed, the normally open main contact 2 of the transformer protection switch element QF is opened, and the transformer disconnects the power supply.
And the secondary control circuit is also provided with a brake-off indicator lamp HG, and the brake-off indicator lamp HG is connected in series with the sixth normally closed auxiliary contact 206 of the transformer protection switch element and then is connected in parallel with the brake-off control circuit of the transformer protection switch element. When the transformer protection switching element QF is switched off, the switching-off indicator HG turns on a green light.
The transformer protection switch element second normally closed auxiliary contact 202 and the transformer protection switch element third normally open auxiliary contact 203 are linked auxiliary contacts, and can be of a single-pole double-throw structure, and when the transformer protection switch element second normally closed auxiliary contact 202 is closed, the transformer protection switch element third normally open auxiliary contact 203 is disconnected; when the transformer protection switching element third normally open auxiliary contact 203 is closed, the transformer protection switching element second normally closed auxiliary contact 202 is opened. The fifth normally open auxiliary contact 205 of the transformer protection switching element and the sixth normally closed auxiliary contact 206 of the transformer protection switching element are linked auxiliary contacts, and may be of a single-pole double-throw structure.
One end of an energy storage motor M in the transformer protection switching element is connected with a power supply, and the other end of the energy storage motor M is connected with a neutral line after being connected with a fourth normally closed contact 204 of the transformer protection switching element in series. The energy storage motor M is used for a spring energy storage type high-low voltage circuit breaker and provides energy for the QF opening and closing of a transformer protection switch element. When the transformer protection switching element QF is switched off, the spring releases energy, the energy storage motor starts to work, and the motor stops after the spring stretches the stored energy to be in place. The embodiment is further provided with a fault indicator lamp HY which is connected in series with the transformer protection switch element alarm contact 207 and then connected in parallel with the magnetizing switch element control circuit. The breaker does not act during the ordinary opening operation and is used for judging whether the breaker trips due to faults or not. When the transformer protection switching element QF is tripped due to a fault, the transformer protection switching element alarm contact 207 is closed, and the fault indicator light HY is turned on.
In this embodiment, two ends of the opening button SB2 are connected in parallel with a temperature control switch, and the temperature control switch is normally open. When the temperature of the transformer protection switch element QF is too high and exceeds the temperature threshold of the temperature control switch in the transformer protection switch element QF in the use process of the transformer, in order to prevent the danger of overheating, fire and the like, the temperature control switch is closed, the opening coil F of the transformer protection switch element QF is electrified, the normally open contact of the transformer protection switch element QF is opened, the normally closed contact of the transformer protection switch element QF is closed, the transformer is powered off, and the same function as that of pressing the opening button SB2 is realized.
In this embodiment, the delay switch element KT is a time relay, the delay closing time of the normally open contact of the time relay is 3 to 5 seconds, and the delay time adopted in this embodiment is 3 seconds. The test shows that the device provides a current with a smaller current relative to the rated current for the transformer when the time is delayed for 3 seconds, so that the transformer generates a back electromotive force in advance to generate an electromagnetic field, the instantaneous electromagnetic field intensity of the transformer reaches about 80% of the rated electromagnetic field of the transformer, and the magnetizing inrush current when the transformer protection switching element QF is switched on is effectively reduced.
In this embodiment, a current fuse FU is further connected in series in the secondary control circuit, one end of the current fuse FU is connected to the power supply, and the other end of the current fuse FU is connected to the input end of the secondary control circuit. The current fuse FU is arranged here, when the current is too large due to abnormal conditions such as short circuit in the secondary control circuit, the current fuse is fused, the secondary control circuit is disconnected, and the damage to components and parts caused by the large current is prevented.
In this embodiment, the primary main circuit is further provided with a magnetizing circuit protection switching element QF1, and the magnetizing circuit protection switching element QF1 is a miniature circuit breaker, needs to be manually switched on, and can be automatically tripped during overload. The magnetizing circuit protection switching element QF1 is arranged between the transformer protection switching element QF and the magnetizing switching element KM; the magnetizing circuit protection switch element QF1 is normally open, one end of a normally open main contact of the magnetizing circuit protection switch element QF1 is connected with the input end of the transformer protection switch element QF main contact 2, and the other end of the normally open main contact is connected with the input end of the magnetizing switch element KM main contact 1. The charging line protection switching element QF1 is used for overload protection of the charging switching element KM and the current limiting elements (R1, R2, R3).
In this embodiment, a magnetizing completion indicator HW is further provided, and the magnetizing completion indicator HW is connected in series with the normally open contact of the time delay switch element KT and then connected in parallel with the magnetizing switch element control circuit. When magnetizing is carried out, because the time delay switch element KT has a time delay process, the normally open contact of the time delay switch element KT is in a disconnected state in the process, and the indicator light HW is turned off after magnetizing; when the magnetizing is finished, the normally open contact of the time delay switch element KT is closed, and the magnetizing finishing indicator light HW is lightened.
The working process is as follows:
1. the device is connected between a low-voltage power supply and a boosting transformer, a magnetizing circuit protection switching element QF1 is switched on firstly, then a switching-on button SB1 is pressed, a control coil of a magnetizing switching element KM is electrified, so that a normally open contact of the magnetizing switching element KM is closed, the device starts to magnetize the transformer when a main contact 1 of the magnetizing switching element KM is closed, and a brake-separating indicator lamp HG is on at the same time;
2. when a normally open contact of a magnetizing switch element KM is closed, a control coil of a time-delay switch element KT is electrified, the time-delay switch element KT starts to count down, when the preset 3-second time delay time is reached, the normally open contact of the time-delay switch element KT is closed, a closing coil X of a transformer protection switch element is electrified, and the normally open contact and the normally closed contact of a transformer protection switch element QF are closed and disconnected; when the transformer protection switching element QF main contact 2 is closed, the transformer is connected to a power supply, and a closing indicator light HR is on; meanwhile, the magnetizing switch element KM controls the coil to lose power, the normally open contact of the magnetizing switch element KM is disconnected, when the main contact 1 of the magnetizing switch element KM is disconnected, the magnetizing is finished, and the magnetizing completion indicator lamp HW is lightened;
3. when the power supply needs to be switched on for the transformer after the power supply is finished, a switching-off button SB2 is pressed, a switching-off coil F of a transformer protection switch element is electrified, a normally open contact of the transformer protection switch element QF is disconnected, a normally closed contact of the transformer protection switch element QF is closed, a main contact 2 of the transformer protection switch element QF is disconnected, and the transformer is switched off the power supply; in the normal use process, if the temperature of the transformer protection switch element QF is too high and exceeds the threshold value of the temperature control switch, the normally open contact of the temperature control switch is closed, the opening coil F of the transformer protection switch element is electrified, and the same function as that of pressing the opening button SB2 is realized;
4. the energy storage motor M provides power for the transformer protection switch element QF contact to act; when the transformer protection switching element QF is tripped due to a fault, the transformer protection switching element alarm contact 207 is closed, and the fault indicator light HY is turned on.
The device is small in size, simple and easy to install and connect, and can stably, safely and smoothly connect a power supply (such as a diesel generator power supply) to the primary side of the transformer so as to realize a power supply function. The device magnetizes the transformer in advance, after magnetizing for several seconds, the instantaneous electromagnetic field intensity of the transformer reaches about 80% of the rated electromagnetic field of the transformer, and the device for eliminating the magnetizing inrush current outputs a control signal to close a transformer protection switch, so that the purpose of reducing and eliminating the magnetizing inrush current of the transformer is achieved, and a power supply is smoothly connected to the transformer. In the access process, high exciting current can not be generated to impact the protection switch element and the transformer of the boosting transformer, and the damage of the power supply, the transformer and the protection switch element of the transformer caused by overhigh current can not be caused.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.
Claims (10)
1. A device for eliminating the magnetizing inrush current is suitable for inhibiting the magnetizing inrush current generated when a power supply is connected into a transformer, and is characterized in that the device is arranged between the power supply and the transformer and comprises a primary main circuit and a secondary control circuit which are formed by combining a transformer protection switching element, a current limiting element, a time delay switching element and a magnetizing switching element, wherein the primary main circuit is connected with the secondary control circuit in parallel; in the primary main circuit, one end of a main contact of the transformer protection switching element is connected with the power supply, and the other end of the main contact of the transformer protection switching element is connected with the primary side of the transformer; one end of a main contact of the magnetizing switch element is connected with the power supply, and the other end of the main contact of the magnetizing switch element is connected with the primary side of the transformer after being connected with the current limiting element in series; one end of the secondary control circuit is connected with the power supply, and the other end of the secondary control circuit is connected with the neutral line; the secondary control circuit comprises a magnetizing switch element control circuit, a time control circuit, a transformer protection switch element closing control circuit and a transformer protection switch element opening control circuit which are respectively connected in parallel; the magnetizing switch element control circuit controls the magnetizing switch element and the time control circuit to be switched on and off; the time control circuit controls the on-off of the switching-on control circuit of the transformer protection switching element; the transformer protection switching element switching-on control circuit controls the switching-on of the transformer protection switching element; the transformer protection switching element opening control circuit controls the opening of the transformer protection switching element.
2. The device for eliminating the magnetizing inrush current of claim 1, wherein the magnetizing switch element control circuit comprises a closing button, a first normally closed auxiliary contact of the transformer protection switch element, and a control coil of the magnetizing switch element, which are connected in sequence, the closing button is connected to the power supply, and the control coil of the magnetizing switch element is connected to the neutral line.
3. The device for eliminating the magnetizing inrush current of claim 2, wherein the first normally open auxiliary contact of the magnetizing switch element is connected in parallel across the closing button.
4. The device for eliminating the magnetizing inrush current of claim 1, wherein the time control circuit comprises a second normally open auxiliary contact of the magnetizing switch element and a control coil of the time delay switch element which are connected in series, and the time control circuit is connected in parallel across the control coil of the magnetizing switch element.
5. The apparatus according to claim 1, wherein the transformer protection switching element closing control circuit comprises the time delay switching element normally open contact, the transformer protection switching element closing coil, and the transformer protection switching element second normally closed auxiliary contact, which are connected in series in sequence, the time delay switching element normally open contact is connected to the power supply, and the transformer protection switching element second normally closed auxiliary contact is connected to the neutral line.
6. The device for eliminating the magnetizing inrush current of claim 1, wherein the transformer protection switching element opening control circuit comprises an opening button, a transformer protection switching element opening coil and a third normally-open auxiliary contact of the transformer protection switching element, which are connected in series in sequence, the opening button is connected with the power supply, and the third normally-open auxiliary contact of the transformer protection switching element is connected with the neutral line.
7. The device for eliminating the magnetizing inrush current of claim 6, wherein a temperature controlled switch is connected in parallel to two ends of the opening button, and the temperature controlled switch is normally open.
8. The device for eliminating the magnetizing inrush current as claimed in claim 1, wherein the time delay switching element is a time relay, and the time delay closing time of a normally open contact of the time relay is 3-5 seconds.
9. The apparatus according to claim 1, wherein a current fuse is further connected in series in the secondary control circuit, one end of the current fuse is connected to the power supply, and the other end of the current fuse is connected to the input end of the secondary control circuit.
10. The device for eliminating the magnetizing inrush current of claim 1, wherein the primary main circuit is further provided with a magnetizing line protection switching element, and the magnetizing line protection switching element is arranged between the transformer protection switching element and the magnetizing switching element; the magnetizing circuit protection switch element is normally open, one end of a normally open main contact of the magnetizing circuit protection switch element is connected with the main contact of the transformer protection switch element, and the other end of the normally open main contact of the magnetizing circuit protection switch element is connected with the main contact of the magnetizing switch element.
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| CN201920723484.0U CN209860589U (en) | 2019-05-20 | 2019-05-20 | Device for eliminating excitation surge current |
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| CN201920723484.0U CN209860589U (en) | 2019-05-20 | 2019-05-20 | Device for eliminating excitation surge current |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114204532A (en) * | 2021-10-25 | 2022-03-18 | 北京无线电测量研究所 | Distribution circuit for reducing starting impact current of transformer in radar system |
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2019
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114204532A (en) * | 2021-10-25 | 2022-03-18 | 北京无线电测量研究所 | Distribution circuit for reducing starting impact current of transformer in radar system |
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