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1-4 L60 Line Phase Comparison Relay GE Multilin
1.2 UR OVERVIEW 1 GETTING STARTED
1
c) UR SCAN OPERATION
The UR-series devices operate in a cyclic scan fashion. The device reads the inputs into an input status table, solves the
logic program (FlexLogic™ equation), and then sets each output to the appropriate state in an output status table. Any
resulting task execution is priority interrupt-driven.
Figure 1–3: UR-SERIES SCAN OPERATION
1.2.3 SOFTWARE ARCHITECTURE
The firmware (software embedded in the relay) is designed in functional modules which can be installed in any relay as
required. This is achieved with Object-Oriented Design and Programming (OOD/OOP) techniques.
Object-Oriented techniques involve the use of ‘objects’ and ‘classes’. An ‘object’ is defined as “a logical entity that contains
both data and code that manipulates that data”. A ‘class’ is the generalized form of similar objects. By using this concept,
one can create a Protection Class with the Protection Elements as objects of the class such as Time Overcurrent, Instanta-
neous Overcurrent, Current Differential, Undervoltage, Overvoltage, Underfrequency, and Distance. These objects repre-
sent completely self-contained software modules. The same object-class concept can be used for Metering, Input/Output
Control, HMI, Communications, or any functional entity in the system.
Employing OOD/OOP in the software architecture of the Universal Relay achieves the same features as the hardware
architecture: modularity, scalability, and flexibility. The application software for any Universal Relay (e.g. Feeder Protection,
Transformer Protection, Distance Protection) is constructed by combining objects from the various functionality classes.
This results in a ’common look and feel’ across the entire family of UR-series platform-based applications.
1.2.4 IMPORTANT CONCEPTS
As described above, the architecture of the UR-series relays differ from previous devices. To achieve a general understand-
ing of this device, some sections of Chapter 5 are quite helpful. The most important functions of the relay are contained in
“elements”. A description of the UR-series elements can be found in the
Introduction to Elements section in Chapter 5. An
example of a simple element, and some of the organization of this manual, can be found in the Digital Elements section. An
explanation of the use of inputs from CTs and VTs is in the Introduction to AC Sources section in Chapter 5. A description of
how digital signals are used and routed within the relay is contained in the Introduction to FlexLogic™ section in Chapter 5.
827823A1.CDR
PKP
DPO
OP
Protective Elements
Protection elements
serviced by sub-scan
Read Inputs
Solve Logic
Set Outputs