ABB ACS800 Series Hardware Manual page 36

36
Start-up order is:
1) Grid air-circuit breaker (MCB1), 2) Grid-side converter contactor (MCB2), 3) Stator air-circuit breaker/
contactor (MCB3)
Shutdown order is reversed:
1) Stator air-circuit breaker/contactor (MCB3), 2) Grid-side converter contactor (MCB2), 3) Grid air-circuit
breaker (MCB1)
Grid air-circuit breaker
(MCB1) closing
(normal run-up)
Grid air-circuit breaker
(MCB1) opening
(normal shutdown)
Grid air-circuit breaker (MCB1)
opening (emergency shutdown –
grid-side converter contactor
(MCB2) fault)
Hardware description
The conditions for closing grid air-circuit breaker (MCB1) are:
• No faults in the hardware monitoring circuit (K24 is closed)
• Stator air-circuit breaker/contactor is open (K31 is open)
• Grid-side converter contactor is open (K41 is open)
• No active fault in the converter (A42/X25:RO1 relay output is active)
If all the conditions are fulfilled, switching on A42/X25:RO2 relay output
will cause grid air-circuit breaker (MCB1) to close.
Normally, grid air-circuit breaker (MCB1) opening is handled by
firmware. When the converter is running, shutting down happens in a
particular order. It starts by opening the stator air-circuit breaker/
contactor (MCB3), relay K31 turns OFF. Then the converter de-
energizes the grid-side converter contactor (MCB2), relay K41 turns
OFF. Once both grid-side converter contactor (MCB2) and stator air-
circuit breaker/contactor (MCB3) are OFF, grid air-circuit breaker
(MCB1) can also be switched OFF by de-activating A42/X25:RO2 relay
output.
In emergency situations when the converter needs to be disconnected
from the grid, the monitoring circuit of the converter shutdown process
is used. Such situations happen if any of MCB devices fails during the
converter shutdown:
1. Grid-side converter contactor (MCB2) FAULT
If the monitoring circuit detects that status of the grid-side converter
contactor is still closed (K41 relay is ON) after the converter tried to
open the contactor and 2 sec time delay has elapsed, grid air-circuit
breaker (MCB1) will be forced to open by de-energizing K24 relay to
disconnect the converter from the grid.