GE B30 Communications Manual page 246

OVERVIEW CHAPTER 3: IEC 61850 COMMUNICATION
The figure shows the timing of GOOSE transmissions.
Figure 3-4: TxGOOSE timing
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When none of the published member values are changing, the GOOSE message is sent periodically to allow subscribers to
monitor the connection. These messages, called heartbeat messages, also allow a subscriber recovering from an
interruption or outage to obtain the values of the members in the absence of event messages. A timeAllowedtoLive field
including in each GOOSE message informs the subscriber of the maximum amount of time to wait for another message
before declaring the connection lost. In UR devices, the heartbeat period is controlled by the TxGOOSE UPDATE TIME
setting, and the timeAllowedtoLive value is controlled by the TIME TO LIVE setting.
When any published member value changes state, the GOOSE message is immediately sent with the new values. Such a
message is called an event message. A short time after the initial event message is sent, it is resent several times. In UR
devices there are normally three retransmissions, with intervals controlled by the TxGOOSE RETRANS TIME settings.
However, if the TxGOOSE RETRANS TIME setting is set to zero, there are no retransmissions.
UR devices implement the publisher side of each GOOSE service under the name TxGOOSE. See the applicable UR
instruction manual for the number of TxGOOSE elements available, and the performance of each.
3-8 UR FAMILY – COMMUNICATIONS GUIDE