There are 64 virtual outputs that may be assigned via FlexLogic™. If not assigned, the output will be forced to 'OFF' (Logic
0). An ID may be assigned to each virtual output. Virtual outputs are resolved in each pass through the evaluation of the
FlexLogic™ equations. Any change of state of a virtual output can be logged as an event if programmed to do so.
For example, if Virtual Output 1 is the trip signal from FlexLogic™ and the trip relay is used to signal events, the settings
would be programmed as follows:
a) REMOTE INPUTS/OUTPUTS OVERVIEW
Remote inputs and outputs, which are a means of exchanging information regarding the state of digital points between
remote devices, are provided in accordance with the Electric Power Research Institute's (EPRI) UCA2 "Generic Object Ori-
ented Substation Event (GOOSE)" specifications.
The UCA2 specification requires that communications between devices be implemented on Ethernet com-
munications facilities. For UR relays, Ethernet communications is provided only on the type 9C and 9D ver-
sions of the CPU module.
The sharing of digital point state information between GOOSE equipped relays is essentially an extension to FlexLogic™ to
allow distributed FlexLogic™ by making operands available to/from devices on a common communications network. In
addition to digital point states, GOOSE messages identify the originator of the message and provide other information
required by the communication specification. All devices listen to network messages and capture data from only those mes-
sages that have originated in selected devices.
GOOSE messages are designed to be short, high priority and with a high level of reliability. The GOOSE message structure
contains space for 128 bit pairs representing digital point state information. The UCA specification provides 32 "DNA" bit
pairs, which are status bits representing pre-defined events. All remaining bit pairs are "UserSt" bit pairs, which are status
bits representing user-definable events. The UR implementation provides 32 of the 96 available UserSt bit pairs.
The UCA2 specification includes features that are used to cope with the loss of communication between transmitting and
receiving devices. Each transmitting device will send a GOOSE message upon a successful power-up, when the state of
any included point changes, or after a specified interval (the "default update" time) if a change-of-state has not occurred.
The transmitting device also sends a "hold time" which is set to three times the programmed default time, which is required
by the receiving device.
Receiving devices are constantly monitoring the communications network for messages they require, as recognized by the
identification of the originating device carried in the message. Messages received from remote devices include the mes-
sage "hold" time for the device. The receiving relay sets a timer assigned to the originating device to the "hold" time interval,
and if it has not received another message from this device at time-out, the remote device is declared to be non-communi-
cating, so it will use the programmed default state for all points from that specific remote device. This mechanism allows a
receiving device to fail to detect a single transmission from a remote device which is sending messages at the slowest pos-
sible rate, as set by its "default update" timer, without reverting to use of the programmed default states. If a message is
received from a remote device before the "hold" time expires, all points for that device are updated to the states contained
in the message and the hold timer is restarted. The status of a remote device, where 'Offline' indicates 'non-communicat-
ing', can be displayed.
The GOOSE facility provides for 64 remote inputs and 32 remote outputs.
GE Power Management
VIRTUAL OUTPUT 1
Virt Op 1
L90 Line Differential Relay
5.7 INPUTS / OUTPUTS
5.7.5 VIRTUAL OUTPUTS
Range: Up to 12 alphanumeric characters
Range: Disabled, Enabled
5.7.6 REMOTE DEVICES