ABB excitation system module UNITROL 1010 3BHE035301R1002 UNS0121A-Z,V1 voltage regulator

Description

Jumper and trigger plate
The trigger unit is a part of the static de excitation device (jumper) UNITROL 1010, and has multiple independent discharge thyristor trigger circuits.
The controlled de excitation circuit of the generator is double redundant and connected with the trip coil of the de excitation switch at the same time.
UNITROL 1010 is equipped with a voltage monitoring circuit, which will automatically trigger the thyristor when the excitation voltage exceeds the set value. Therefore, as an independent over-voltage protection device, the jumper can protect the thyristor and field winding from the impact of dangerous over-voltage spikes.
Rotor grounding protection

One point grounding of rotor has little impact on steam turbine generator unit, and it is generally allowed to continue to operate for a period of time. After the generator set is grounded at one point, the potential of each part of the rotor to the ground changes, which is easy to induce two-point grounding. Once the turbine generator is grounded at two points, the consequences are quite serious. The rotor body is burned because the fault point flows through a considerable fault current; As some windings are short circuited, the current in the excitation winding increases, which may cause burns due to overheating; Because part of the windings are short circuited, the air gap magnetic flux is unbalanced, which causes vibration. The excitation circuit is grounded at two points, which can also magnetize the shafting and turbine.
The excitation circuit is grounded at two points. Even if the protection acts correctly, it is too late to prevent the cylinder and the main shaft from being magnetized. The consequences caused by the two-point grounding fault in the excitation circuit are very complex and troublesome to deal with.
In recent years, the installation of one point grounding protection for large turbine generators has been a final conclusion, and there is no objection at home and abroad. However, there are different views on whether the one point grounding protection acts on the signal or trips. For those who advocate acting on signals, consider installing two-point grounding protection; Those who advocate the action of shutdown consider that it is unnecessary to install two-point grounding protection, which is conducive to avoiding turbine magnetization. In addition, since there is still a lack of two-point grounding protection device for excitation circuit with good selectivity, high sensitivity, frequent operation and mature operation experience, there is also a suggestion not to install two-point grounding protection. Many imported large units do not install two-point grounding protection.
ABB’s UNITROL 5000 excitation system is equipped with a bridge type rotor grounding protection device. Their design idea for rotor grounding protection is: when the insulation resistance of the excitation circuit drops to a certain value, an alarm will be given, and when the insulation resistance continues to drop to a certain value, the protection will act to cut off the generator set, so as to prevent catastrophic accidents caused by two-point connection.
Inspection before power on
Before the excitation system is put into operation, it must be ensured that all required power supplies have been supplied and can be safely started. The following checks must be carried out:
The system maintenance has been completed;
The control and power cabinet is ready for operation;
The control power supply and regulator power supply of the de excitation switch have been energized;
No alarm and fault information is generated;
Switch excitation system to remote control mode;
Switch the excitation system to automatic operation mode;
The generator reaches the rated speed.

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