AVR+Intelligent Device for Voltage Regulation and On Load Tap Changer(OLTC) Monitoring

With  innovative  resources  for more  accurate  voltage  regulation,  the  AVR+  Intelligent  Device  by Treetech  goes  beyond  a  traditional  regulating  relay,  allowing  smart  voltage  regulation,  better  energy quality and smaller losses.

The OLTC maintenance management optional functions permit the optimization and reduction ofmaintenance costs, are extended if associated with thermal monitoring with the OLTC temperature differential by TM1/TM2 module and mechanical monitoring with the torque signature function in the IDM module. Itspatented pending features(Brazil and abroad), make it the most complete and efficient available. These features are:

• Multiple regulation setting adjustments available for the user, activated via scheduling date and time or through remote control;
• Communication Protocols: Modbus-RTU and DNP 3.0; Serial and Ethernet capability
• One RS 485 port for integrated operation with the SPS paralleling supervisors, which makes it unnecessary to use the COMM-04 communication module and provides information and commands through communication protocols;
• Current measurement with a clip-on transformer thus increasing safety for the installation and maintenance personnel;
• Multi-measuring Functionality: indication of voltages on the transformer and the load; voltage deviations; current; active, reactive and apparent power; power factor and frequency;
• Adjustable PT/CT lag, from 0-330deg, thus allowing any kind of PT/CT connection;
• Independent actuation times to raise and lower voltage, with linear timing modes, linear in steps or reverse curve;
• Compensation of line drop through Resistance or Reactance adjustments or through the simplified voltage drop percentage method
• OLTC blocking in case of overcurrent and undervoltage. If overvoltage occurs: OLTC blocking orrapid voltage reduction.
• One or three tap measuring inputs allowing the control of three single-phase transformers in one bank. Local/Remote and Manual/Automatic OLTC control.
• Paralleling control between transformers or banks through the Master-Slave, Circulating Current methods, or a combination of both methods, in the case of single-phase banks;
• Automatic blocking of a triggered OTLC;
• OLTC Maintenance Assistant by number of tap position changes and contact wear;
• Six signalling relays with programmable functionalitys and operation type (NO/NC);
• Three programmable analog outputs selectable for variable remote indication, programmable output range: 0…1, 0…5, 0…10, 0…20, or 4…20 mA
• The combination of two analog outputs offers bipolar operation, with the following ranges: -1…1, -5…5, -10…10, -20…20 mA;
• Four inputs for dry contacts for remote commands, such as regulation set change, paralleling control and others;
• Rugged construction, exceeding the required EMC standards, to operate in severe electromagnetic conditions found in substations and operating temperatures of -40 to 85degC;
• Universal power supply of 38 to 265 Vac/ 38 to 275 Vdc, 50/60Hz.
• Compact size, saving space and reducing panel costs;
• High brightness VFD display, readable under any lighting and temperature conditions;
• Non-volatile mass memory for measurements and alarms.
• Maintenance free internal clock without batteries.

Position Measurement

• An input to measure the position of the OLTC with a potentiometric transmitter, with compensation for cable resistance and error detection. Associated functions:
• Current output programming for TAP remote indication;
• OLTC local manual command (front panel) and through serial communication;
• Restriction of the OLTC course range (minimum and maximum allowed TAPs) and memorization of the maximum and minimum positions reached since the last reset;
• Protection against improper OLTC operations: OLTC is blocked if operations that were not initiated by the AVR+are performed.

Master-SlaveParallel Control

• Parallel control of up to 6 three-phase transformers or 6 single-phase transformer banks through the Master-Slave method. Each AVR+ can control one three-phase transformer or three single- phase transformers in a bank.

Circulating CurrentParallel Control

• Parallel control of up to 6 transformers or 6 banks via the Minimum Circulation Current, blocking excessive circulating current.

OLTC Maintenance

• OLTC operation counter, with maintenance reminder based on number of operations;
• Integration of switching current squared, with a setting for maintenance based on a high total Isquared sum.
• Forecast of the remaining time before the next OLTC maintenance.
• Programmable maintenance warnings issued in advance.