Other Functions; Alarms; Local User Interface; Time Synchronization - GE UR Series Instruction Manual

2 PRODUCT DESCRIPTION

2.5 OTHER FUNCTIONS

2.5 OTHER FUNCTIONS

2.5.1 ALARMS

The relay contains a dedicated alarm relay, the Critical Failure Alarm, housed in the Power Supply module. This output
relay is not user programmable. This relay has Form-C contacts and is energized under normal operating conditions. The
Critical Failure Alarm will become de-energized if the relay self test algorithms detect a failure that would prevent the relay
from properly protecting the transmission line.
2

2.5.2 LOCAL USER INTERFACE

The relay's local user interface (on the faceplate) consists of a 2 × 20 vacuum florescent display (VFD) and a 22 button key-
pad. The keypad and display may be used to view data from the relay, to change settings in the relay, or to perform control
actions. Also, the faceplate provides LED indications of status and events. The operation of the keypad is discussed in the
HUMAN INTERFACES chapter.

2.5.3 TIME SYNCHRONIZATION

The relay includes a clock which can run freely from the internal oscillator or be synchronized from an external IRIG-B sig-
nal. With the external signal, all relays wired to the same synchronizing signal will be synchronized to within 0.1 millisecond.

2.5.4 FUNCTION DIAGRAMS

Figure 2–3: L90 BLOCK DIAGRAM
GE Power Management L90 Line Differential Relay 2-11