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OVERVIEW
Description of DGT system operation
UTILITY
SUBSTATION
2
3
Relay
DGT-U
Breaker
1. Fault in power line or distribution system.
2. Relay at substation detects fault.
3. Relay sends trip command to DGT-U.
4. DGT-U wirelessly sends trip command to DGT-R.
5. DGT-R transfers trip command to DGT-D at DG site.
6. Breaker at DG site trips.
7. DGT-D unit sends status confirmation to DGT-R.
8. DGT-R transfers status info back to DGT-U.
1–2
Figure 1-1: Note icons used in the documentation
NOTE
The standard note icon emphasizes a specific point or indicates minor problems that may
occur if instructions are not properly followed.
The caution icon indicates that possible damage to equipment or data may occur if
instructions are not properly followed.
The danger icon provides users with a warning about the possibility of serious or fatal
injury to themselves or others.
Figure 1-2: Typical DGT system
4
DGT-R
7
COMM
TOWER
FAULT
1
DGT-U
Recloser
(optional)
In Figure 2, DGT-U units installed at the Utility Substation and Recloser sites continuously
monitor the trip status and transmit that status every 28 to 56 milliseconds to DGT-D units
installed at the Distributed Generation sites. At the DGT-D locations the trip status is wired
into breaker device. An auxiliary contact from the breaker is wired back into the DGT-D.
The DGT-D units continuously monitor the status of the auxiliary contact and transmit that
status every 28-56 milliseconds back to the DGT-U units constantly confirming current
status. All communication is coordinated through the DGT-R Unit in order to achieve
maximum range.
If a trip condition is detected by the Utility's equipment, the trip status is energized at the
DGT-U. When the DGT-D units receive the energized trip status, the output status will
disconnect the Breaker device at the Distributed Generation site. The status of auxiliary
contact from the breaker is also energized and transmitted back to the DGT-U thereby
confirming that the Trip has occurred.
DGT DISTRIBUTED GENERATION TRIP CONTROL SYSTEM – INSTRUCTION MANUAL
CHAPTER 1: INTRODUCTION
CAUTION
DANGER
DISTR. GENERATION
OWNERS
GEN SITE #1
5
DGT-D
GEN SITE #7
5
DGT-D
Relay
6
Breaker
Relay
6
Breaker
887001A1
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