Technical Specifications

FAQ

1. What is the ABB REM 545 Machine Protection Terminal used for?
The ABB REM 545 is a dedicated machine protection terminal designed primarily for generators and large motors. It can be used as the main protection system for generator and generator-transformer units in small and medium-power diesel, hydroelectric and steam power plants. It is also suitable for medium-voltage synchronous motors and large asynchronous motors used in applications such as pumps, mills and crushers. The terminal combines protection, measurement, monitoring, control, programmable logic and communication functions in one device.

2. What types of generator protection can the REM 545 provide?
The REM 545 supports a broad range of generator protection functions. Depending on the configured functionality, it can provide short-circuit and earth-fault protection as well as overcurrent, voltage, frequency, excitation, impedance and power-related protection. Reverse-power or motoring protection is particularly useful for generators because it can detect a generator being driven as a motor. Multiple protection stages can be independently configured with appropriate operating delays and setting values for selective protection coordination.

3. What motor protection functions are available in the REM 545?
For motor applications, the REM 545 can monitor operating conditions such as phase current, unbalanced load, voltage, frequency and motor start-up behavior. Motor start-up supervision can help detect abnormal acceleration or prolonged starting conditions. Stall protection and cumulative start-up counting can also be used to protect motors from repeated or excessive starting stress. These functions make the terminal suitable for demanding applications involving pumps, mills, crushers and other large rotating machines.

4. What CT and VT inputs does the ABB REM 545 support?
The REM 545 supports conventional measuring transformers as well as compatible current sensors and voltage dividers, depending on the hardware configuration. Current inputs are available for 0.2 A, 1 A and 5 A rated secondary circuits, while voltage inputs can be configured for commonly used 100 V, 110 V, 115 V or 120 V nominal values. Correct CT ratio, polarity, phase sequence and VT wiring are essential because measurement errors can directly affect protection calculations and may result in incorrect protection operation.

5. Does the REM 545 provide measurement and monitoring functions in addition to protection?
Yes. The REM 545 is designed as an integrated machine terminal rather than a protection-only relay. It can measure phase currents, phase-to-phase and phase-to-neutral voltages, neutral current, residual voltage, frequency, power factor, active power, reactive power and energy. These measurements can be used for local monitoring, control logic, alarms and higher-level automation. Optional RTD/analog I/O can also be used for temperature monitoring, such as stator winding, bearing or ambient temperature measurements.

6. Can the REM 545 be integrated into a substation automation system?
Yes. The REM 545 supports serial and optical communication functions for integration into protection and automation systems. Depending on the installed communication hardware, it can communicate with higher-level control or monitoring systems using supported protocols and interfaces. IEC 61850 connectivity can be implemented through the appropriate SPA-ZC 400 adapter. Optical communication is also useful where fast, electrically isolated communication is required between protection devices and the substation control system.

7. Does the ABB REM 545 have programmable logic functions?
Yes. Integrated PLC functionality allows the REM 545 to perform programmable control and automation tasks. Logic can be used for interlocking, start and stop sequences, alarm handling, protection coordination and other application-specific control functions. This reduces the need for separate external control relays in some installations. When modifying the logic, the existing protection scheme and interlocking relationships should be reviewed carefully because an incorrect logic configuration can affect both machine control and protection behavior.

8. What should be checked when troubleshooting an ABB REM 545?
Troubleshooting should normally begin with the auxiliary power supply, terminal diagnostics and active alarms. Next, check CT and VT wiring, phase sequence, digital input signals and output relay circuits. If measured values are abnormal, verify the transformer ratios, polarity and parameter settings before assuming that the terminal hardware is defective. For communication problems, inspect the communication interface, protocol configuration, addressing and connected gateway or adapter. Protection trips should also be reviewed through event and disturbance records to determine whether the operation was caused by a genuine machine fault, incorrect settings, wiring problems or an external operating condition.