DC electromotor speed adjuster

The main functions of the system

1.Control function

The full open distributed I/O system established with PROFIBUS, with rapid control over the response, high coordination synchronism and control precision, strong anti-interference capability, can program the special process procedures according to the different processes and fully meet the process requirements and the onsite control functions. It has strong expanded function, as to the points that are deemed to be controlled, monitored and protected, it can be conveniently introduced.

The control function is divided into internal and external control, the internal control means the local control, namely control over the single onsite equipment on the control cabinet so as to carry out the single commissioning and overhaul convenient. This function can be realized through the communication; the external control means the centralized control; the large and medium sized PLC of Siemens is the core of the system control; the control will be realized through PLC and the external extensive module, the operation and the monitoring will be centralized on the operation desk and the central control machine. This function is mainly realized through PROFIBUS communication

2.Display function

2.1 Control cabinet unit: display the basic parameters and states of the units: armature voltage, armature current, excitation current, speed of rotation and basic state indication.

2.2 The DC speed adjustment unit hans strong display capabiliyt through PMU equipped with front panel

·It can display the operation state (RUN/READY/FAULT) of the present equipment.

·Full digitalized display of the function, process parameters or the percentage in the set values, the display precision is high, including voltage, current and speed of rotation, incoming frequency, triggering angle, accepted data and so on; through the external definition and connection, it can also display the temperature rise, temperature, input and output state and so on.

·Full computerization of diagnosis, automatically display the default (alarm) code and automatically lock and store the first default (alarm) so as to find out the default reasons conveniently.

2.3 The operation desk can display the states and parameters in the centralization mode according to the need

·It can display the indexes that shall be paid greatest attention to in the system. The display is accurate and convenient, the operator can master the operation condition of the equipment in the first time, depending on the specific process, in common sense, including speed of rotation, voltage, current, flow, pressure and so on; it can be displayed digitally or analogously.

·Indication of the basic operation state. Each unit allow for the starting, switching-in indication, switching-off indication and default indication an so on.

·Adjustment mode, functional parameters of auxiliary equipment and state monitoring

2.4Central control machine: the industrial process control software WINCC is built in the machine with rich function. The function of the menu is powerful. All of the measured values will be accurately detected and calculated to ensure the high precision and accuracy. UPS will be special allocated, even if the power network meets with failure of power of default, the default records and operation parameters will not be lost so that the maintenance personnel can analyze and check it conveniently.

• Dynamically display the quantity to be monitored. Digitalized display and high precision.
• Specially set and modify the process parameter (online), monitor the actual values monitored and fed back in real time for comparison. In principle, the parameter is not allowed to be modified after being set.
• The random or error operation can be prevented through the limitation of authority.
• Monitor the parameters with reference value in real time, draw the analogous curves and put on record; the sampling of the data shall be accurate, the period shall short, the precision shall be high and the time of keeping on the record can be adjusted.
• Specially display the default information, monitor in real time and put it on the record. Each item includes the time, date, lasting time, message text (default description) of the default, error point, help text and message types and so on.

3.Default protection function

·Over-voltage protection, under-voltage protection, over-high and over-low protection of power frequency.

·Protection of over-current, over-load and short circuit.

·Fault containment of excitation loop: under-excitation, phase voltage, default of fuse and so on

·Phase voltage default protection of armature power

·Default protection of electric panel power supply

·Over-temperature protection of motor

·Default of speed measurement and feedback unit protection

·Overtime protection of communication and bus-bar default protection

·Default of elements of thyristor protection

·External default protection: oil return, cooling water and lubrication, oil pressure, oil temperature, tensile and so on

·Interface default protection.

Speed adjustment unit and the main performance parameters

1. unit

The core part of the DC speed adjustment system is the DC speed adjustment unit, which can be divided into reversible and irreversible speed adjustment unit

The irreversible speed adjustment unit (deregeneration feedback controller) is composed of full control thyristor bridge with perfect dynamic protection and overload protection, and the related electric control lines. It can provide accurate speed of torque control in the selected rotation direction. It is mainly used for the mechanical equipment of single way operation or not frequently commutation or without strict requirement on the commutation speed. Therefore, in case that the irreversible speed adjustment unit needs commutation, it can adopt the commutation mode of contactor.

Reversible speed adjustment unit (regeneration feedback controller) is composed of two full thyristor bridges and one advanced electric control line and it can provide the acceleration, deceleration, speed of rotation and torque control. It is mainly used in the mechanical equipment of frequent commutation or with the requirement on the quick commutation speed.

All types of the armature controllers provide a standard field regulator, which is composed of a full-wave semi-control single-phase thyristor bridge with dynamic and overload protection and can provide the constant voltage source or constant current source in the application of the constant torque according to the selected operation mode. The operation function of the exciting current can be further enhanced to provide weak magnetic function of magnetic felid to the system requiring increasing speed or constant power control.

The control loop and the power loop are entirely separated, in this way, the connection among the controllers within a system is simplified and the security of the operation is improved. In case of the frequency within 45-65 Hz and interfered power supply, the control loop has strong anti-interference capability and the armature controller has no requirements on the phase order.

The internal unit of the WZX series DC speed adjustment usually adopts Siemens 6RA70 or Oulu 590 series full digital DC speed adjustment unit

2.Mail electric performance

2.1 Performance and characteristics of Oulu 590+ series DC speed adjustment unit:

590+ is the latest DC speed adjustment unit of Oulu and it is the new edition/reinforcement edition of 590C series widely accepted by the users at home.

It has the following new characteristics

(a)Small volume, the volume of 590+ with new structure is 40% smaller than the one of 590C

(b)Many communication modules can be selected, for example PROFIBUS, MODBUS, DEVICENET, E-BISYCN and LINK and so on

(c)Analog input and output point with high resolution (12bit); simple control panel, provide the local/external operation mode; the loca operation mode is conveniently used for the initial use and commissioning

(d)590+ selects the speed feedback, speed measurement motor panel/optical code panel, which are same to 590C

(e)The writing method is same to 590C;the wiring terminal on the control panel is same to the one of 590C

(f)All of them adopt the software to define the voltage/current of the armature/magnetic field

2.2 Performance and characteristics of SIEMENS 6RA70 series DC speed adjustment unit:

·6RA70 is a new generation full digital DC speed adjustment product based on 6RA23/24 and it has the following main characteristics compared to other products

·Rated output armature current of the single unit:15A-2000A, rated exciting current: 3A-85A

·After the unit is connected in parallel, the rated output armature current can reach up to 12000A

·The input voltage can be divided into five grades: 400V/460V/575V/690V/830V

·Strong communication capacity. With SIMOLINK high-speed unit-unit communication, supporting PROFIBUS, CAN-BUS, DEVICENET and USS protocol

·All process panels, communication panels and OPIS operation panel can be put in circulation with the new generation SIMOVERT MASTERDRIVES vector control AC speed adjustment products.