Frame switch with motor protector

Abstract

The utility model discloses a frame switch with a motor protector, which comprises a total current loop and a motor protector tripping circuit, the total current loop is respectively provided with current transformers TA1 on three phases A, B and C of leading-out wires of a frame switch cable, and a zero sequence current transformer TA0 is arranged outside the leading-out wires of the three phases A, B and C; the current transformer TA1 and the zero sequence current transformer TA0 are respectively connected with the motor protector MD, the motor protector tripping circuit comprises a protection action node of the motor protector MD and a coil of an intermediate relay K which are connected in sequence, and a series branch of a normally open contact of the intermediate relay K and a tripping pressing plate X2 of the motor protector is connected with the frame switch in parallel. According to the scheme, the inherent technical defects existing when the 400V frame switch intelligent tripper is used for protecting the motor are overcome, the protection sensitivity of the 400V motor is improved, and safe and stable operation of each large 400V motor is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power plant motor protection, in particular to a frame switch with motor protector. BACKGROUND

[0002] 400V large motor generally adopts frame switch power supply mode, and intelligent tripping device provides protection function for the motor, but when the 400V frame switch intelligent tripping device is used for motor protection, there is inherent technical defect, the inverse time long delay protection has no motor start locking function, in order to avoid motor starting current, the tripping device long delay setting is relatively long, the protection setting can only provide protection during the starting process, and the protection, especially the 400V hot air recirculation fan motor starting time in the power plant, is the longest, and after repeated tests, the time setting is 16s (that is, 6 times of long delay current value 16s tripping; 1.5 times of long delay current value 256s tripping) to ensure reliable starting, even if the long delay current value is set as the rated current of the motor, the protection sensitivity of the motor is not enough when the motor is slightly blocked and overloaded, and if the current abnormally increases in a small range during operation, the operator cannot find it in time, which will cause the motor to overheat and burn. SUMMARY

[0003] The purpose of the present application is to provide a frame switch with motor protector, which realizes the inverse time long delay protection of the frame switch intelligent tripping device and the time limit starting overprotection of the motor protector during the motor starting process, and ensures the safe and stable operation of the motor.

[0004] In order to achieve the above purpose, the present application realizes the following technical scheme.

[0005] A frame switch with motor protector, comprising a total current loop and a motor protector tripping circuit;

[0006] The total current loop is provided with a current transformer TA1 on each of three-phase frame switch cable outgoing lines A, B and C, and a zero sequence current transformer TA0 is arranged outside the three-phase outgoing line cables, and the current transformer TA1 and the zero sequence current transformer TA0 are connected with the motor protector MD respectively;

[0007] The motor protector tripping circuit comprises a protection action node of the motor protector MD and an intermediate relay K coil connected in sequence, and the normally open contact of the intermediate relay K is connected in series with the motor protector tripping pressure plate X2, and the series connection is connected in parallel with the frame switch.

[0008] Further, the total current loop is provided with an intelligent tripping device TK on each of three-phase frame switch cable outgoing lines A, B and C.

[0009] Further, the motor protector MD is installed on the front panel of the frame switch, and the intermediate relay K is installed on the inner rail of the frame switch.

[0010] Further, the frame switch with motor protector further comprises a control power supply, a power supply module, a closing and opening control loop and an on-site protection loop.

[0011] The motor protector MD collects three-phase current of the three-phase current transformer TA1 installed on the three-phase cable outgoing lines A, B and C of the frame switch to realize the motor protector time limit starting over-time protection during the motor starting process. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The utility model discloses a frame switch with motor protector. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the accompanying drawings in the embodiments of the present application.

[0014] The present embodiment discloses a 400V motor frame switch with a motor protector.

[0015] Table 1: Frame switch intelligent tripping device TK setting table

[0016]

[0017] Inverse time overload long delay 256S will act trip, according to the field experience now motor can keep 60S or so under 1.5 times rated current, 256S such long time motor must be overheated and burn loss. 400V motor frame switch only adopts the self-contained intelligent tripping device TK, and the motor slight stall and overload protection sensitivity is seriously insufficient in normal operation, which cannot meet the 400V motor protection requirements.

[0018] After the motor protector MD is added, the total current circuit is provided with the current transformer TA1 on the three-phase A, B, C outgoing lines of the frame switch cable, and the zero sequence current transformer TA0 is provided outside the three-phase outgoing lines of the cable, and the current transformer TA1 and the zero sequence current transformer TA0 are connected with the motor protector MD. The motor protector MD is installed on the front panel of the frame switch, and the intermediate relay K is installed on the inner rail of the frame switch. The intelligent tripping device TK is further provided on the three-phase A, B, C outgoing lines of the frame switch cable in the total current circuit.

[0019] The motor protector tripping circuit comprises the protection action node of the motor protector MD and the coil of the intermediate relay K connected in sequence, and the series branch of the normally open contact of the intermediate relay K and the motor protector tripping pressure plate X2 is connected in parallel with the frame switch.

[0020] In the embodiment, the 400V motor has a rated power of 160kW, a rated current of 298.2A and a rated rotating speed of 990r / min. The intelligent tripping device TK of the frame switch can provide the inverse time overload long delay protection, the definite time short circuit protection, the instantaneous short circuit protection and the definite time ground fault protection when the 400V motor is protected. The motor protector MD can provide the definite time starting overtime protection, the definite time overload protection, the definite time overcurrent stall protection, the definite time short circuit protection and the definite time ground fault protection when the 400V motor is protected.

[0021] The motor protector definite time starting overtime protection in the motor starting process is realized by collecting the current of the three-phase current transformer TA1. The motor protector definite time overload protection, the definite time overcurrent stall protection in the normal operation with the starting lock function, the definite value setting only considering the normal operation condition and not considering the starting process condition, and the motor protector MD definite value table in Table 2 are referred to.

[0022] Table 2 Motor protector MD definite value table

[0023]

[0024] The motor protector short circuit protection in the whole process is participated. The motor protector ground fault protection is realized by collecting the current of the zero sequence current transformer TA0.

[0025] When the motor is abnormal, the motor protector MD protection action MD: 6 / 7 contact is closed, the frame switch tripping circuit is started through the motor protector tripping pressure plate X2, the frame switch is disconnected, and the motor is protected by isolating the fault point.

[0026] Finally, it should be noted that the above description is only the preferred embodiment of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A frame switch with motor protector, characterized in that The total current circuit, the motor protector tripping circuit; The total current circuit is provided with current transformers TA1 on three-phase frame switch cable outgoing lines A, B and C respectively, and is provided with a zero sequence current transformer TA0 outside the three-phase outgoing line cables; the current transformers TA1 and the zero sequence current transformer TA0 are connected with the motor protector MD respectively; The motor protector tripping circuit comprises a protection action node of the motor protector MD and an intermediate relay K coil connected in sequence; the normally open contact of the intermediate relay K is connected in series with a series branch of the motor protector tripping pressure plate X2 and is connected in parallel with the frame switch.

2. The frame switch with motor protector of claim 1, wherein, The total current circuit is further provided with an intelligent tripper TK on the three-phase frame switch cable outgoing lines A, B and C.

3. The frame switch with motor protector of claim 1, wherein, The motor protector MD is installed on the front panel of the frame switch, and the intermediate relay K is installed on the inner rail of the frame switch.

4. The frame switch with motor protector of claim 1, wherein, The control power supply, the power supply module, the opening and closing control circuit and the local protection circuit are further included.

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