1 GETTING STARTED
a) UR BASIC DESIGN
The UR is a digital-based device containing a central processing unit (CPU) that handles multiple types of input and output
signals. The UR can communicate over a local area network (LAN) with an operator interface, a programming device, or
another UR device.
The CPU module contains firmware that provides protection elements in the form of logic algorithms, as well as program-
mable logic gates, timers, and latches for control features.
Input elements accept a variety of analog or digital signals from the field. The UR isolates and converts these signals into
logic signals used by the relay.
Output elements convert and isolate the logic signals generated by the relay into digital or analog signals that can be used
to control field devices.
b) UR SIGNAL TYPES
The contact inputs and outputs are digital signals associated with connections to hard-wired contacts. Both 'wet' and 'dry'
contacts are supported.
The virtual inputs and outputs are digital signals associated with UR-series internal logic signals. Virtual inputs include
signals generated by the local user interface. The virtual outputs are outputs of FlexLogic™ equations used to customize
the device. Virtual outputs can also serve as virtual inputs to FlexLogic™ equations.
The analog inputs and outputs are signals that are associated with transducers, such as Resistance Temperature Detec-
The CT and VT inputs refer to analog current transformer and voltage transformer signals used to monitor AC power lines.
The UR-series relays support 1 A and 5 A CTs.
The remote inputs and outputs provide a means of sharing digital point state information between remote UR-series
devices. The remote outputs interface to the remote inputs of other UR-series devices. Remote outputs are FlexLogic™
operands inserted into IEC 61850 GSSE and GOOSE messages.
The direct inputs and outputs provide a means of sharing digital point states between a number of UR-series IEDs over a
dedicated fiber (single or multimode), RS422, or G.703 interface. No switching equipment is required as the IEDs are con-
nected directly in a ring or redundant (dual) ring configuration. This feature is optimized for speed and intended for pilot-
aided schemes, distributed logic applications, or the extension of the input/output capabilities of a single relay chassis.
Figure 1–2: UR CONCEPT BLOCK DIAGRAM
L90 Line Current Differential System
1.2.2 HARDWARE ARCHITECTURE
1.2 UR OVERVIEW