Internal faults - Arc protection - Bay control and measurement - Merging unit - Transformer protection - 2 winding - Feeder protection - Voltage regulation - Capacitor bank protection - Grid automation - Busbar differential protection (high impedance) - Line differential protection - Back-up protection - Motor protection - Busbar protection (voltage and frequency) - Interconnection protection - Generator protection - Power management/Load shedding - Operation Manual - REX615 Protection and control - Relion Protection and Control - PCL2 - IEC - ANSI - 30.10.2025

REX615 Operation Manual

When an internal relay fault is detected, relay protection operation is disabled, the green Ready LED begins to flash and the self-supervision output contact is activated.

Note: Internal fault indications have the highest priority on the LHMI. None of the other LHMI indications can override the internal fault indication.

An indication about the fault is shown as a message on the LHMI. The text Internal Fault with an additional text message, a code, date and time, is shown to indicate the fault type.

Different actions are taken depending on the severity of the fault. The protection relay tries to eliminate the fault by restarting. After the fault is found to be permanent, the protection relay stays in the internal fault mode. All other output contacts are released and locked for the internal fault. The protection relay continues to perform internal tests during the fault situation.

If an internal fault disappears, the green Ready LED stops flashing and the protection relay returns to the normal service state.

The self-supervision signal output operates on the closed-circuit principle. Under normal conditions, the protection relay is energized and the contact gaps 3-5 in slot X100 is closed. If the auxiliary power supply fails or an internal fault is detected, the contact gaps 3-5 are opened.

Figure 1. Output contact

The internal fault code indicates the type of internal relay fault. When a fault appears, the code must be recorded so that it can be reported to ABB customer service.

Table 1. Internal fault indications and codes

Fault indication

Fault code

Additional information

Fast self-recovery attempt (# of attempts)

Slow 10 min self-recovery (# of attempts)

Immediate permanent IRF-mode

Action in permanent fault state

Internal Fault System error

2

Start up error: HW/SW mismatch

No

No

Yes

If relay SW has just been updated, redo it. If not recovered, contact your nearest ABB representative to check the next possible corrective action.

Internal Fault System error

2

Start up or runtime error: Data bus error, CPU module

Yes (2)

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault System error

2

Start up error: SCL file missing

No

No

Yes

Do factory restore or rewrite configuration using PCM600.

Internal Fault System error

2

Start up error: Missing order number

No

No

Yes

Do factory restore. If not recovered, contact your nearest ABB representative to check the next possible corrective action.

Internal Fault System error

2

Start up error: FPGA HW error, CPU module

Yes (2)

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault System error

2

Start up error: FPGA image corrupted, CPU module

Yes (2)

Yes (3)

No

Restart the relay or if relay SW has just been updated, redo it. If recovered by restarting, continue relay normal operation. If not recovered by restarting or redoing SW update, replace the relay, most probably hardware failure in CPU module.

Internal Fault System error

2

Runtime error: CPU internal fault

Yes (2)

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault File system error

7

Start up error or runtime error: file system error

Yes (2)

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault Test

8

Internal fault test activated manually by the user.

No

No

-

Just check the "Internal fault test" -setting parameter position, if relay is in test mode

Internal Fault SW watchdog error

10

Start up error: Watchdog reset has occurred too many times within an hour. Note! This is different indication than Warning code 10: Watchdog reset

No

No

Yes

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay.

Internal Fault SO-relay(s),X105

40

Runtime error: Faulty Signal Output relay(s) in card located in slot X105.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X105.

Internal Fault SO-relay(s),X115

41

Runtime error: Faulty Signal Output relay(s) in card located in slot X115.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X115.

Internal Fault SO-relay(s),X100

43

Runtime error: Faulty Signal Output relay(s) in card located in slot X100.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X100.

Internal Fault SO-relay(s),X110

44

Runtime error: Faulty Signal Output relay(s) in card located in slot X110.Runtime error:

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X110.

Internal Fault SO-relay(s),X120

45

Runtime error: Faulty Signal Output relay(s) in card located in slot X120.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X120.

Internal Fault SO-relay(s),X130

46

Runtime error: Faulty Signal Output relay(s) in card located in slot X130.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X130.

Fault in PO-relay(s) attached to X105

50

Runtime error: Faulty Power Output relay(s) in card located in slot X105.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X105.

Fault in PO-relay(s) attached to X115

51

Runtime error: Faulty Power Output relay(s) in card located in slot X115.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X115.

Internal Fault PO-relay(s),X100

53

Runtime error: Faulty Power Output relay(s) in card located in slot X100.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X100.

Internal Fault PO-relay(s),X110

54

Runtime error: Faulty Power Output relay(s) in card located in slot X110.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X110.

Internal Fault PO-relay(s),X120

55

Runtime error: Faulty Power Output relay(s) in card located in slot X120.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X120.

Internal Fault PO-relay(s),X130

56

Runtime error: Faulty Power Output relay(s) in card located in slot X130.

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X130.

Internal Fault Light sensor error

59

Runtime error: Faulty ARC light sensor input(s).

Yes (2)

Yes (3)

No

Check wirings. Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the communication module including ARC inputs in slot X000.

Internal Fault Conf. error,X105

60

Start up error: Card in slot X105 is wrong type, is missing, does not belong to original configuration or card firmware is faulty.

No

No

Yes

Check that the card in slot X105 is proper type and properly installed. Check that the plug-in unit is properly installed and plug-in unit handle is properly fixed to closed position. Then restart the relay. If does not recover by restarting, it is hardware module failure most likely. Exchange the hardware module in slot X105.

Internal Fault Conf. error,X115

61

Start up error: Card in slot X115 is wrong type, is missing, does not belong to original configuration or card firmware is faulty.

No

No

Yes

Check that the card in slot X115 is proper type and properly installed. Check that the plug-in unit is properly installed and plug-in unit handle is properly fixed to closed position. Then restart the relay.If does not recover by restarting, it is hardware module failure most likely. Exchange the hardware module in slot X115.

Internal Fault Conf. error,X000

62

Start up error: Card in slot X000 is wrong type, is missing, does not belong to original configuration or card firmware is faulty.

No

No

Yes

"Check that the communication card in slot X000 is proper type and properly installed. Check that the plug-in unit is properly installed and plug-in unit handle is properly fixed to closed position. Then restart the relay. If does not recover by restarting, it is hardware module failure most likely. Exchange the communication module in slot X000. In some rare cases also communication storm may cause this. Detach the ethernet communication cable(s) from the communication module and reboot the relay. If not recover,exchange the communication module in slot X000. "

Internal Fault Conf. error,X100

63

Start up error: Card in slot X100 is wrong type, is missing, does not belong to original configuration or card firmware is faulty.

No

No

Yes

"Check that the card in slot X100 is proper type and properly installed. Check that the plug-in unit is properly installed and plug-in unit handle is properly fixed to closed position. Then restart the relay. If does not recover by restarting, it is hardware module failure most likely. Exchange the hardware module in slot X100."

Internal Fault Conf. error,X110

64

Start up error: Card in slot X110 is wrong type, is missing, does not belong to original configuration or card firmware is faulty.

No

No

Yes

"Check that the card in slot X110 is proper type and properly installed. Check that the plug-in unit is properly installed and plug-in unit handle is properly fixed to closed position. Then restart the relay. If does not recover by restarting, it is hardware module failure most likely. Exchange the hardware module in slot X110."

Internal Fault Conf. error,X120

65

Start up error: Card in slot X120 is wrong type, is missing, does not belong to original configuration or card firmware is faulty.

No

No

Yes

"Check that the card in slot X120 is proper type and properly installed. Check that the plug-in unit is properly installed and plug-in unit handle is properly fixed to closed position. Then restart the relay. If does not recover by restarting, it is hardware module failure most likely. Exchange the hardware module in slot X120."

Internal Fault Conf. error,X130

66

Start up error: Card in slot X130 is wrong type, is missing, does not belong to original configuration or card firmware is faulty.

No

No

Yes

"Check that the card in slot X130 is proper type and properly installed. Check that the plug-in unit is properly installed and plug-in unit handle is properly fixed to closed position. Then restart the relay. If does not recover by restarting, it is hardware module failure most likely. Exchange the hardware module in slot X130."

Internal Fault Card error,X105

70

Card in slot X105 is faulty.

Yes (2)

Yes (3)

No

Exchange the hardware module in slot X105.

Internal Fault Card error,X115

71

Card in slot X115 is faulty.

Yes (2)

Yes (3)

No

Exchange the hardware module in slot X115.

Internal Fault Card error,X000

72

Card in slot X000 is faulty.

Yes (2)

Yes (3)

No

"Check the plug-in unit connector pins in the card by detaching the plug-in unit. If pins are OK, exchange the communication module in slot X000. In some rare cases also communication storm may cause this. Detach the ethernet communication cable(s) from the communication module and reboot the relay. If not recover,exchange the communication module in slot X000. "

Internal Fault Card error,X100

73

Card in slot X100 is faulty.

Yes (2)

Yes (3)

No

Exchange the hardware module in slot X100.

Internal Fault Card error,X110

74

Card in slot X110 is faulty.

Yes (2)

Yes (3)

No

Exchange the hardware module in slot X110.

Internal Fault Card error,X120

75

Card in slot X120 is faulty.

Yes (2)

Yes (3)

No

Exchange the hardware module in slot X120.

Internal Fault Card error,X130

76

Card in slot X130 is faulty.

Yes (2)

Yes (3)

No

Check the plug-in unit connector pins in the card by detaching the plug-in unit. If pins are OK, exchange the hardware module in slot X130.

Internal Fault LHMI module

79

Runtime error: LHMI LCD error. The fault indication may not be seen on the LHMI during the fault.

Yes (2)

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, check LHMI connection cable and connection to be proberly fixed. If then not recovered by restarting, exchange the LHMI module.

Internal Fault RAM error

80

Runtime error: Error in the RAM memory on the CPU module.

Yes (2)

Yes (10)

No

If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault ROM error

81

Runtime error: Error in the ROM memory on the CPU module.

Yes (2)

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault EEPROM error

82

Start up error: Error in the EEPROM memory on the CPU module.

No

No

Yes

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault EEPROM error

82

Start up error: CRC check failure in the EEPROM memory on boot-up on the CPU module.

Yes (2)

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault FPGA error

83

Runtime error: Error in the FPGA on the CPU module.

Yes

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault RTC error

84

Start up error: Error in the RTC on the CPU module.

Yes

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, replace the relay, most probably hardware failure in CPU module.

Internal Fault RTD card error,X105

90

Runtime error: RTD card located in slot X105 may have permanent fault. Temporary error has occurred too many times within a short time.

Yes (2)

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the RTD hardware module in slot X105.

Internal Fault RTD card error,X130

96

Runtime error: RTD card located in slot X130 may have permanent fault. Temporary error has occurred too many times within a short time.

Yes

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the hardware module in slot X130.

Internal Fault COM card error

116

Runtime error: Error in the COM card.

Yes

Yes (3)

No

Restart the relay. If recovered by restarting, continue relay normal operation. If not recover by restarting, exchange the communication module in slot X000.

For further information on internal fault indications, see the operation manual.