SR489-P5-LO-A20-E GE 4-20 mA analog output relay

Description

Stator Thermal Protection

The 489 provides thermal modeling overload protection to prevent generator damage caused by generator overheating. The thermal model algorithms incorporate current unbalance biasing and RTD biasing which provides accurate modeling of the actual generator temperature. The 489 can be configured to trip the generator offline when the generator’s thermal limits are reached, or close an Alarm contact that signals operations personnel to take appropriate actions.

Bearing Overtemperature

Twelve RTD inputs are provided that may be configured to monitor and protect against bearing overtemperature conditions. The 489 provides the option for using RTD voting which requires that two RTDs simultaneously indicate an overtemperature condition before it will trip the generator offline. RTD voting provides additional security against tripping of generators when an invalid overtemperature signal is received from a malfunctioning RTD.

Negative Sequence Overcurrent

Rotor thermal protection is provided through monitoring of negative sequence current, which is a significant contributor to rotor heating, to ensure it does not increase above the generator’s capability limits. The 489 provides a negative sequence definite time overcurrent alarm element and a negative sequence timed overcurrent curve tripping element to ensure the generator stays within it’s short time and continuous negative sequence current rated limits.

The stability, reliability, and widespread application of DCS systems in industrial production processes have led to increasing demands on the entire system. Although the DCS system adopts advanced technology and has powerful functions, there are still many problems in practical applications. In addition to factors such as design, installation, and management, there may also be failures such as hardware failures, software failures, local equipment failures, and malfunctions caused by human error. System faults can be divided into fixed faults and accidental faults, which are global faults that affect the operation of the system. A fault that can restore the system to normal by restarting after a fault occurs is called an accidental fault; On the contrary, faults that cannot be restored to normal after a system restart and require the replacement of hardware or software systems are called fixed faults, usually caused by improper system design or long system operation years.
The main reasons for hardware failures include poor quality of components, improper usage conditions, corrosion and aging of components, improper adjustment, and short circuits caused by incorrect wiring introducing abnormal voltage. Sometimes, system hardware failures can also occur due to environmental factors such as temperature, humidity, dust, vibration, impact, and rodent infestation on site.

DPU failures mainly include DPU disconnection, initialization, and dual machine switching failures, which can be determined by the DPU status indicator light. Among them, initialization is the most common, mainly due to differences in the lower computer programs or system files between the main and secondary DPUs (incompatible versions of the DOC chip can also cause such failures). The solution is to copy the files of the main control DPU to the initialized DPU (under normal dual machine switching) and write them to the electronic disk.

There are many reasons for the disconnection of DPU, such as corrosion and aging of electrical components, burning of components due to poor heat dissipation, explosion of main board capacitors, short circuit of electrical components due to large dust accumulation on the board, and poor contact of communication terminals; In addition, the high load rate of DPU can also lead to DPU crashes, DCS system failures, and other failures. The solution to this type of fault is to restart the DPU, and if the electrical components are damaged, repair or replace the spare parts in a timely manner. Dual machine switching failures are mainly caused by communication failures, such as poor communication port contact, communication cable failure, dual machine switching card failure, poor anti-interference ability of the processor, unreasonable network cable laying, and high processor load rate. Communication cable failures can also lead to DPU initialization and disconnection failures.