Synchronous motors excitation systems

• on-load operation from no-load to the rated one and with motor accepted overload;
• operation with impact and alternating motor load;
• stable operation in transient and underexcitation motor accepted modes;
• automatic and manual modes of excitation current control;
• manual regulation of excitation current;
• automatic regulation of:
  • motor stator voltage for regulation of motor supply network voltage;
  • motor reactive power for reactive power compensation upon its fixed level in the network;
  • motor COS (φ) for mechanisms with alternating load;
  • reactive power in remote load unit for reactive power compensation at area, workshop and substation input;
• main regulated parameter (excitation current, stator voltage, motor reactive power or COS (φ)) control with accuracy of 0,5 — 1,0 % of the set static characteristic;
• testing of exciter before startup:
  • starting resistance circuit continuity checking;
  • exciter and excitation circuit current checking.

Exciters consist of two structural units supplied as a package:

• converter cabinet with built-in accelerating resistor;
• armored power matching transformer.

Local monitoring and control means on the door include: control devices, lamps, buttons and switches, excitation setters, control terminal, other monitoring and control means upon Customer’s request.

All local monitoring and control means can be duplicated on a remote control desk. Extended ambient temperature operational range: built-in automatic heating system (option).

VTE, VTP (hereinafter “exciter”) can be supplied from one input with voltage of ~380 V, 50 Hz. It is also possible to supply control means from a separate input. Voltage input = 220 (110) V is provided for oil circuit breaker closing and opening circuits control. Circuit and structure of exciter relay switching part is defined by requirements of specified application object.

Exciter rectifier has a three-phase bridge circuit with one thyristor in arm. Starting resistance is connected parallel to the load (synchronous motor excitation winding) via contactless key on thyristors. It is provided for asynchronous start and reduction to permissible value of overvoltage arising in rotor winding, when motor is in asynchronous operation modes.

Key thyristors are closed by microprocessor control system in start mode, as well as directly due to overvoltage arising at excitation winding.

Exciter monitoring and control:

• local — monitoring and control from cabinet door;
  • switching of exciter automatic and manual operation modes;
  • excitation setting control in manual and automatic modes;
  • startup or motor startup permission;
  • motor parameters monitoring by means of devices: stator current, excitation current and voltage, COS (φ);
  • exciter regulation and protections system state monitoring by means of control terminal;
• remote — monitoring and control by means of remote panel. Remote panel duplicates all devices and controls, located on the exciter door, except control terminal. Monitoring and control from remote panel is identical with monitoring and control from the exciter door;
• remote — monitoring and control from Automatic Process Control System via network interface:
  - switching of automatic excitation regulator operation modes (excitation current regulation, reactive power, COS (φ), etc.);
  - automatic excitation regulator resetting;
  - startup permission and prohibition;
  - motor parameters monitoring;
  - exciter regulation and protections system state monitoring.

Interfaces (option)

• capability of integration into area or workshop Automatic Process Control System via serial interfaces Profibus-DP, Modbus, Ethernet, CAN;
• automatic excitation regulator open structure for Automatic Process Control System response via network interfaces.

Protection system:

• converter overvoltage protection;
• converter internal short circuits protection;
• maximum excitation current protection;
• excitation loss protection;
• rotor overvoltage protection;
• delayed start protection;
• asynchronous operation protection;
• stator current transformers open circuit protection — at motor startup;
• motor stop under excitation protection;
• stator switch auxiliary contacts failure protection;
• converter thyristors conductivity monitoring, exciter operation continuation without conductivity of one of thyristors;
• excitation circuit resistance monitoring: cable, brush gear, rotor winding in order to prevent contact connections degradation, brush gear failure, rotor overheating, etc.;
• external protections: receipt of external protections contact signals (vibration, oil grease, bearings temperature, etc.) with possibility of warning signaling forming, as well as with time delay, emergency shutdown.

Built-in device for automatic excitation regulator and motor parameters and state recording with archiving function:

• number of simultaneously recorded parameters — 1...16;
• resolution of recording in time — 3,3...100 ms;
• recorded sample duration — 1.5…30 s;
• number of data samples archived in case of emergency shutdowns — 4;
• recording of archive samples date and time storage in real time values;
• graphic visualization of recorder archive and current data using specialized laptop based software and diagnostics suite.