Circulation pump motor protection transformation program.

The rated capacity of the motor is 2000kW or more or less than 2000kW, but the motor with insufficient current-sensitive protection and protection sensitivity should be equipped with longitudinal differential protection. Currently, the traditional longitudinal differential is widely installed, but the current is unbalanced. With regard to these drawbacks, the magnetic balance differential protection has been proposed and applied in foreign countries, which fundamentally solves the problems of unbalanced CT characteristics on both sides and unbalanced outputs of differential protection currents. In 2003, Fujian Meizhouwan thermal power plant applied this technology to the technological transformation of circulating pump motor protection and achieved good results.

1 Magnetic balance differential protection 1.1 Principle Magnetic balance differential protection is to connect the beginning of the winding of each phase of the motor and the terminal lead to the ring core window of the current transformer, and the magnetic balance principle of the excitation of the primary coil of the current transformer is used. The composition of the high-sensitivity current protection, as shown in the figure.

During the normal operation or start-up of the motor, the starting lead and the terminal lead current of each phase are input and output, and the excitation ampere of the primary transformer side is zero. Therefore, the secondary side of the current transformer has no output and will not cause the protection to malfunction.

1.2 advantages compared to the traditional longitudinal differential protection L2.0 traditional motor protection on both sides of the C6 magnetization characteristic curve is difficult to be consistent, therefore, the two sides of the C6 characteristics of the mismatch becomes longitudinal differential protection unbalanced One of the important reasons. In order to escape the unbalanced current, only the high differential protection start value can be picked up, which will directly lead to a decrease in the differential protection sensitivity. For magnetic balance differential protection, because the primary current difference is already balanced on the primary side of the same C6, there are no two C6 secondary current imbalance problems.

022 Under normal operating conditions, if the C6 is opened on the secondary side, it will not only cause the traditional differential protection to malfunction, but also cause serious over-voltage and endanger the safety of equipment and personnel. However, for the magnetic balance differential protection, since the C6-sub side difference current during normal operation is zero, that is, the C6 secondary current is zero, the above problem does not occur.

L2.7 If traditional longitudinal differential protection is used, it is imperative to install a set of C6 on each side of the motor; however, magnetic balance differential protection requires only one set of 96, which eliminates the need to add another set of differential C6, which reduces the cost.

2 Selection of Differential Protection for Circulating Water Pumps in Meizhou Bay Thermal Power Plant 2.1 Introduction to Circulating Pump Motor Protection = 4, Each unit is equipped with two 720034 circulating pumps manufactured by HabC, each circulating pump can be installed with a circulating pump at the main building The original circulating water pump motor protection is installed in the corresponding unit 6kV switch room, equipped with a set of CT for measuring phase current (for quick-break overcurrent protection, overload protection, unbalanced current protection, mechanical stall protection), with a measurement zero Sequential current CT (for ground zero-sequence protection), one temperature-measured RTD for motor stator and bearing temperature protection %, overvoltage, undervoltage, and reverse phase sequence protection are installed, but no longitudinal differential is installed at the time of production protection.

2.2 Technical plan for the technical design of circulating pump motor protection The longitudinal differential protection shall be installed in accordance with national standards. The author gives the following two design options: 2.2.1 Option One! Longitudinal differential protection First of all, on the basis of preserving all kinds of original protection designs and wiring, a set of CTs is installed on the neutral side of the motor, and it is composed of a secondary cable and phase current protection CT for 6 kV switches. Differential circuit.

Or add two sets of CTs on the two sides of the circulating water pump motor to constitute a differential circuit, and send the differential protection signal to the 6kV switch room.

Its advantage is to retain all kinds of original protection design and wiring.

The CT magnetization characteristic curves on both sides of the motor are difficult to be consistent, and there are CT imbalance problems on both sides. In normal operation, if the CT secondary circuit is broken, it will not only cause differential protection misoperation, but also cause serious The overvoltage will endanger equipment and personal safety; 4.15km of secondary cable AC impedance will far exceed the allowable impedance value of the secondary side of CT, and will increase the project cost; two sets of CT will be needed to constitute a differential circuit. Increased costs.

It is necessary to solve the long-distance transmission problem of the snoring signal.

2.2.2 Scheme 2: Magnetic Balance Differential Protection First, on the basis of retaining the original various protection designs and wiring, a set of magnetic balance CT is added on-site in the circulating water pump motor to form a magnetic balance differential circuit. The differential protection relay signal is sent back to the 6kV switch room.

All kinds of protection design and wiring are retained; when the motor is not in failure, the magnetic equilibrium of the ampere turns is applied on the primary side of the CT, and there is no unbalanced current in the differential relay, so there is no CT imbalance problem.

Due to the magnetic balance of the excitation ampere on the primary side of the current transformer, even if the current transformer is disconnected on the secondary side, it will not cause overvoltage.

Disadvantages: It is necessary to solve the long-distance transmission problem of the snoring signal.

2.3 Circulation pump motor protection technical transformation program selected after comparison that program two (magnetic balance differential protection) obviously dominant, so decided to install magnetic balance differential protection in the circulating pump room.

Local installation of magnetic balance CT ratio of 50/5, the correct level of choice 0.5, short-circuit capacity of 8kA. Differential protection relay selection 4E's SR469 motor protection relay.

The R1 output E1/F1 of the SR469 relay is a normally open contact, which is used to protect the exit signal of the slamming; R2 output E3/F3 is a normally closed contact, used to protect the alarm signal of the slamming; the R6 output of the SR469 relay is F8/E9. Normally open contact, used for abnormal device alarm signal. In normal operation, R6 outputs open contact signal. When SR469 relay is de-energized, R6 output contact is changed to close contact signal; but it is still necessary to solve differential protection. Long distance transmission problems.

2.4 Use of optical fiber to achieve long-distance transmission of the snoring signal If it is designed according to the traditional stumbling circuit, due to the reason of 4.15km distance, the secondary impedance of the stumbling circuit is very large and cannot meet the technical requirements of the snoring relay.

Therefore, in this technical reform, we used an optical fiber communication device (MT80 optical fiber transmission device/MR80 optical fiber receiving device) to send the differential protection action back-off signal back to the main building, successfully solving the problem that the secondary circuit of jumper has too large impedance. The problem.

Because MR80 optical fiber receiving device output empty contact capacity is only 100W, can not be used for circulating water pump motor switching noise; therefore, the need to increase the OMRON fast intermediate outlet relay in the main plant, the MR80 optical fiber receiving device output open point is converted to a closed point ( It not only increases the contact capacity, but also meets the requirement of accessing the DCS system of the main building), and is used to control the switching of the circulating pump.

The use of optical fiber as the transmission channel for the signal of a distress signal, but also to consider the monitoring of the optical fiber transmission channel. Therefore, the closed contact signal output from R6 is connected to the MT80 optical fiber transmission device so as to monitor the operating status of the optical fiber channel and optical fiber communication device (MT80 optical fiber transmission device/MR80 optical fiber optical receiver device).

3 Equipment selection and commissioning Installation experience 3.1 Differential relay selection Differential relay impedance must match the current transformer excitation impedance, in order to obtain the maximum volt-ampere number from the current transformer in the relay, thus ensuring the occurrence of single within the motor When phase-to-earth fault occurs, the differential relay works in the most sensitive state.

(turning to page 46) a jargon of the information system. Relay protection and fault recorder information processing systems focus on the collection, storage and application of fault data. With the continuous access of substations, grid fault information will gradually realize systemicity, compactness and standardization. Based on this, The system will be able to implement functions such as fault diagnosis, assisting decision-making in troubleshooting, and provide data for analysis of power grid transient characteristics, stability analysis and control.

Series Number Security Label Sticker

Two hologram stickers with matching serial numbers are commonly used to authenticate collectible merchandise and memorabilia. Typically, one sticker is used to authenticate the collectible product and the matching hologram sticker is used on a certificate of authenticity. When have series number, you will know which number is missing.

Series Number Security Label Sticker,Security Label Stickers,Series Number Label Sticker,Series Number Security Sticker

Shenzhen Tuteng Anti-Counterfeiting Co., Ltd. , https://www.holographicsticer.com