General characteristics
The set of equipment enables regulation of melting power in AC arc furnace, contains controllers for a high-voltage switch, furnace slope and oscillation, roof lifting and lowering:
- metal weight for melting in furnace:
• up to 50 tons; - types of power control:
• manual;
• automatic; - electrode drive types:
• DC drive;
• AC drive; - electrode drives rated parameters range:
• rated current up to 50 A;
• rated voltage up to 460 V;
• unregulated excitation for DC drives, 220 V. - number of independent electrode drives:
• 3 + 1 backup; - controlled parameters of smelting:
• arc current;
• arc voltage;
• smelting power (active and reactive);
• energy consumed during smelting process (active and reactive energy); - furnace mechanisms controlling features:
• furnace slope;
• roof lifting and lowering;
• furnace rolling out and roof retraction. - complete set:
• full completeness – without using elements of the former furnace;
• partial completeness – using elements of the former furnace:
– power transformer;
– furnace slope;
– roof lifting and lowering;
– furnace rolling out and roof retraction; - network interfaces: Profibus DP, Modbus RTU, Ethernet, CAN etc.
Technical specifications
General characteristics
The set of equipment consists of three main cabinets:
- Furnace control cabinet designed to control furnace transformer and furnace power circuit;
- Furnace control panel designed to control the smelting process;
- Electrode motor control cabinet designed to control electrode positioning and regulate melting power.
In addition to these cabinets, the scope supply can be extended with these items:
- Cabinet with transformers and switches, which contains electrode drives power transformer, contactors and automatic switches for furnace auxiliary devices;
- Furnace mechanisms control panels designed to control such furnace mechanisms as arch, slope, furnace rollout;
- Smelter remote console designed to control furnace slope during tapping.
Engineering information
Equipment parameters:
| Parameter | Value |
| Electrode drive | |
| Drive type | thyristor reversible electric drive |
| Rectification circuit | Bridge 6-pulse circuit, reactor or transformer circuit |
| Rectification circuit | 380V |
| Power supply frequency, Hz | 50 |
| Output power of one drive, kVA | up to 30 |
| Rated output voltage, V | 110-460 |
| Rated output current, A | 10-50 |
| Excitation type | Independent non-regulated |
| Excitation voltage, V | 220 |
| Cooling | Natural |
| Type of feedback for speed control | EMF, pulse sensor, tachogenerator |
| allowable current load modes, not exceeding, nom | 2,8 |
| voltage regulation range for EMF feedback | 25:1 |
| voltage stabilization error,%, not exceeding | 5 |
| rectified current stabilization error in the current limiting mode,%, not exceeding | 2 |
| Power controller feedback | Arc voltage and current |
|
Furnace transformer control |
|
| Rated arc current, kA | up to 10 |
| Rated arc voltage, V | up to 300 |
| current emergency shutdown ration, p.u. | up to 4.0 |
Operation conditions
| – altitude above the sea level | – up to 1000 m; |
| – permissible ambient temperature:
during operation, degrees C during storage, degrees C |
– from -10 till +45°С; – from -25 till +60 0С; |
| – permissible humidity at temperatures:
25 degrees C,%, not exceeding 35 degrees C,%, not exceeding |
– 80; – 90; |
| – environment | – non-explosive,
– non-containing harmful impurities and conductible dust, reducing the level of insulation in unacceptable limits; |
| – operational conditions group | – M2 according to GOST17516-72. The floor vibration level where the ES is installed, within the frequency range of 10-50 Hz, should be with an acceleration not exceeding 4.9 m/s?; |
| – seismic rating
– permissible deviation from the vertical position for cabinets installation |
– magnitude 9 (nine) as per MSK-64 (horizontal acceleration – 0,3g)
– not exceeding 5 degrees; |
| – climatic version | – UHL (boreal climate);
– TV (tropical climate) |
| – location category | – 4 |
Scope of cabinets and equipment
Composition of the electrode motor control cabinet:
- Four independent electric drives:
• Drive 1-3 for regulation of arc currents of phases A, B, C;
• Drive 4 is a backup drive common to phase drives. - Non-regulated excitor.
- Content of each drives:
• auxiliary power supply system;
• control system:
– controller with the following functions: control, power adjustment and drive protection;
– analog and discrete input devices;
– devices for thyristor control pulses amplification;
– reversible power bridge;
– external network interface module;
– console for parameters input and drive operation control:
• relay equipment;
• self-contained recorder;
• local control tolls and alarm system on the door;
• cabinet heating device (optional, for the design of drive to be used under low temperature conditions);
Composition of electric furnace control panel:
- Switches for setting arc current, three independent channels for phases A, B, C:
• rough setting, from 0 to 120% in 20% increments;
• precise setting, from -10 to 5% in 5% increments. - Switch for setting the dead zone of the arc power regulator: 0, 2, 5, 10%;
- Switches for arc control modes, three independent channels for each phase A, B, C: manual-automatic;
- Switches for drives operation modes, three independent channels for each phase A, B, C: main-standby;
- Switches for electrode control in manual mode, three independent channels for phases A, B, C;
- Electrodes forced boost button;
- Drive emergency shutdown button;
- High-voltage switch control breaker;
- Electrode drive starter control button;
- Transformer off-circuit tap-changer;
- Display Devices:
• arc currents for each phase;
• arc voltage for each phase;
• smelting power;
• tapping step number of the off-circuit tap-changer. - Arc current relay for each phase;
- Relay equipment and light alarm.
Composition of the electrical furnace control cabinet:
- relay equipment for protection and switching of power circuits and furnace transformer.
Functional characteristics
Automatic power controller:
- power control is carried out by electrode-positioning above the furnace charge. As the distance between the charge increases, the arc resistance grow, which leads to an increase in the voltage drop across the arc and a current decrease in the circuit of transformer secondary winding-electrode-arc-charge. Reducing the distance leads to the opposite effect;
- The power control system consists of three independent regulators, each for regulating an individual electrode position;
- As a feedback the following signals are used: signals from current transformers located in the transformer secondary winding and signals from arc voltage transformers connected according to “dummy zero” circuit;
- The control system speed of response depends on the type of drive used (direct or alternating current), the mechanical connection of electrode motors and P setting of furnace power controller.
Protection system:
- maximum arc current protection;
- time-current protection;
- maximum drive current protection;
- loss of excitation on drive;
- against transformer failure;
- protection against oil overheating in the transformer;
- transformer gas protection.
Network interfaces:
- ProfibusDP;
- ModBusRTU;
- Ethernet;
- CAN etc.
Note: type of the protocol is agreed between the parties during engineering stage.
Recording and diagnostics tools:
- a recorder built into controllers of Electrode Motor Control Cabinet (EMCC):
• analog channels – 1 … 24;
• discrete channels – 1 … 32;
• measuring resolution – 3.3 … 100 ms;
• recording fragment length – 0.5 … 50 seconds;
• data storing for emergency shutdowns – 90 fragments; - a recorder separated from the EMCC controllers for independent control of operation:
• 32 channels of analog sensor signals, discrete input and output signals;
• measuring resolution – 250 µs;
• recording fragment length – 0.5 … 50 seconds;
• data storing for emergency shutdowns – 10 fragments.
The advantage of the built-in recorder lies in the possibility to register internal parameters (parameters of control and protection systems, etc.).
The advantage of an independent recorder lies in a high measuring resolution.
- event logging built into controllers of EMCC:
• input control signals;
• output alarming and tripping signals;
• change of excitation system’s operation modes;
• exceeding and lowering by analog signals of specified limiting values;
• messages of control, regulation and protection systems displayed on the excitation system console terminal; - software for a diagnostic console and a laptop enabling graphical visualization of data from recorders and text visualization of logged data.
Setup and diagnostic complex
- The setup and diagnostic complex is implemented on the basis of a portable computer and intended for:
• graphical visualization of data from the built-in recorder;
• reports storing by set-points;
• controller reprogramming; - The programmable setup complex consists of:
• a portable computer (it is possible to use the Customer’s own portable computer);
• adapter to connect a portable computer to the controller;
• software package.
Note: the setup and diagnostic complex software is free and is available on the manufacturer’s website: pcomplex.ua
Software content:
- Utility “Link” provides for:
• console terminal mode;
• dual-channel oscilloscope mode with display of any control and protection system parameters from the available parameters list;
• work with the built-in program recorder in the converter:
– start / stop the recorder;
– data download after manual or emergency stop of the recorder;
– download of data restored from NOVRAM, previous emergency shutdowns;
– data save to a disk and upload of recorded data from disk;
– display of recorded data in form of tables and graphically;
– display of emergency, warning and service messages list from the control system at the time of shutdown, as well as the time of recorder shutdown. - Utility “Code ReadWriter” ensures:
• download (archive) from the controller to computer hard drive of NOVRAM copy as a .bin file;
• upload from computer hard drive to the controller a previously saved NOVRAM copy as a .bin file;
• importing to a file in the text form for the subsequent report on current values ??of set-points;
• copy, for the purposes of archiving, of the controller’s program in the form of a .bin file;
• reprogramming the controller.
Note: the controller can be reprogrammed using a file previously stored in the archive, or received from the manufacturer, for example, via the Internet, in order to supplement the furnace control system with any specific functions as per agreed Terms of Reference.
Scope of delivery
Equipment composition:
- electrode motor control cabinet – 1 pc.
- electric furnace control cabinet – 1 pc.
- electric furnace control panel – 1 pc.
- cabinet with transformers and switches – 1 pc.
- steelmaker’s remote control panel – 1 pc.
- furnace mechanisms control panel – 1 pc.
- spare parts kit – 1 pc.
- set of maintenance documentation on paper and electronic media – 1 pc.
Additional and supplementary equipment:
- Full set of redundancy boards for the furnace control system – 1 pc.
- High-voltage unit – 1 pc.
- Setup and diagnostic complex: – 1 pc.
• Portable computer
• Adapter to connect a portable computer to the ES
• Software package - Diagnostic panel (RC) on the basis of personal computer – 1 pc.
Safety requirements
- The design and electrical diagrams of furnace control system are implemented in accordance with requirements of the Electrical Installations Rules (EIR);
- The furnace control complies with the safety requirements of GOST 12.2.007.0 and GOST 12.2.007.1, as well as the requirements of Regulations for Operation of Consumer Electrical Installations;
- The excitation system cabinet doors, which give access to conducting parts, have locks and can be opened with special keys;
- The cabinet external surface heating temperature in the most heated, hardly accessible point (except for the power converter transformer) does not exceed 70 ° C under normal operating conditions.
- The design of the furnace control system ensures fire safety due to:
• use of non-combustible and low-combustible materials;
• keeping necessary distances between differently potential conducting parts, as well as between conducting parts and the frame, use of insulating non-combustible partitions in necessary cases;
• use of safety facilities to ensure rapid de-energization of current-carrying parts; - Noise characteristics and permissible sound pressure levels correspond to GOST 12.1.003-83 “SSBT NOISE General requirements” and do not exceed 80 dB.