Abstract：In view of the characteristics of the mine flameproof feeding switch control system, UniMAT Yiwei Company has developed a special mine three-phase AC and leakage monitoring module for three-phase electrical measurement, which can realize the measurement of phase voltage, current, zero-sequence voltage, zero-sequence current and leakage resistance. The results show that the use of UniMAT CPU224+ mine three-phase AC and leakage monitoring module not only reduces the cost, but also meets the national standard for leakage protection, simplifies the configuration scheme, optimizes the program design, and easily upgrades the scheme from the basic KBZ630Z to the more demanding KBZ800Z and KBZ1000. Z and other models, expanded, three-phase AC and leakage monitoring module can be used in various AC monitoring system, in various occasions play a greater role。

Keywords: three-phase AC monitoring, UniMAT PLC, CPU224, EM231, feed switch

1. System overview

Mine Flameproof Vacuum Feed Switch (hereinafter referred to as Feed Switch) is mainly used in underground coal mine. It is used as the main switch and branch switch of power supply system or as the feed switch of mine Flameproof mobile substation (opening the rear cover) in the line of AC 50Hz, voltage 1140V, rated current 400A, 500A, 630A, 800A respectively. The board can also be used as a large capacity motor for infrequent starting. It has the functions of overload, short circuit, under voltage, leakage protection (selective leakage protection) and leakage blocking. The product can be applied to the monitoring system of coal mine safety in mine flameproof vacuum feed switches.

2. system configuration and function realization

1). Hardware configuration of KBZ630Z control system

Display: a 4 line Chinese character text display screen with a protection level of IP65.

Programmable controller: UN200 series CPU224Q UN 214-1AF23-0XB0 piece.

Expansion module: three-phase AC and leakage monitoring module UN 231-0BH22-0XA0

(Note: type KBZ800Z requires two three-phase AC and leakage monitoring modules)

2).system architecture

The system consists of a control system consisting of UniMAT PLC and text screen and an executive system consisting of a vacuum circuit breaker. As shown in the figure. The CPU carries on some logic control, and the mine module mainly collects AC voltage, current and leakage resistance signals, so as to realize the system monitoring and control and complete the leakage locking, overload, short circuit, phase breaking, under-voltage and over-voltage protection functions, with the advantages of high intelligence, stable performance and reliable operation

3). system difficulties

The system is mainly to ensure that the leakage protection action time is less than 50ms and the short-circuit protection action time is less than 100ms, so to ensure that the CPU acquisition and processing speed is very fast, UniMAT PLC uses high-frequency microprocessor, instruction processing speed is 3-10 times higher than ordinary PLC, UniMAT UN200 PLC acquisition and control cycle time is 12ms. Plus peripheral equipment time 30ms, a total of 42ms, to achieve the standard requirements of the device.

4). monitoring function design

Adopting text display screen and cooperating with UniMAT UN200 series small PLC, it can display and memorize the working state, parameters and fault types of feed switch, and can modify and adjust the specific parameters. It has friendly user interface and good man-machine conversation function. It can greatly improve the efficiency of judging and removing faults.

All analog signals are processed into digital signals, which have the characteristics of strong anti-interference ability, simple wiring, large amount of information, reliable and accurate control.

It has complete functions of self-test, self-diagnosis and fault simulation experiment, and can conveniently check whether the protection and control system is normal or not.

5). system function realization

The feeder switch fully considers the working environment of coal mine, and integrates machinery manufacturing, automation, measurement and control technology, instrumentation, computer application technology and other disciplines. Its main technical indicators are as follows:

Voltage level: 1140V/660V; frequency: 50HZ;

The total rated current is 800A and 1200A, and the working current of single unit can reach 400A.

Leakage blocking protection: additional DC detection, 1140V-40K Europe, 660V-22K Europe;

Leakage protection action: 1140V-20K Europe, 660V-11K Europe;

Short circuit protection: 3-10 times the rated current.

Overvoltage and undervoltage protection: 0.75Ue<U<1.15Ue;

Over temperature protection and over limit protection.

The switch equipment has a leakage test and an over current test button, and it can detect the feeding switch protection function at any time

At present, most domestic feeder switches adopt Siemens + transmitter + leakage protector control scheme, although the scheme can meet the system requirements, but there are great limitations in the control function. By using this scheme instead of the above scheme, the process parameters such as current and voltage of the feed switch can be measured on-line. The cost of the customers is reduced, the stability of the technological conditions is ensured, and the response speed of the products is improved. Using text display screen, using the alarm information reflected by the display screen, the staff can easily troubleshoot the fault. The production efficiency is improved.

6. system highlights

The three-phase AC and leakage monitoring module UN 231-0BH22-0XA0 used in the system is a bright spot. The module can collect AC information through AC transformer, and cooperate with CPU operation and control, can realize the functions of over-voltage, under-voltage, overload, short circuit, leakage, three-phase unbalance protection and so on. Insulation resistance monitoring; zero sequence voltage and zero sequence current acquisition function. The product is an extension module of UN200PLC.

Secifications：

The module can also be applied to a variety of power supply monitoring and control products, such as various electrical control distribution system monitoring, small substation monitoring system and other combination switches.

3.Applications effect analysis

This control system achieves the anticipated goal in the feeder switch system. According to the importance of feeder switch system in practice, the UN200 series PLC and three-phase AC and leakage monitoring module of Shenzhen Yiwei Automation are selected. The stability of the system is improved, the response requirement of the system is reached, the wiring construction is simplified and the maintenance is reduced. Difficulty, because the series of PLC and Siemens S7-200 PLC are fully compatible, reducing the difficulty of engineer development, but also to a certain extent to save the cost of the system. The system is in good condition after being put into operation. It is also applied to monitor the power supply screen of several automatic control systems. It has a good application prospect in the industry.