3- Buscoupler [Compatibility Mode]
Transcript of 3- Buscoupler [Compatibility Mode]
Manual Bus Transfer
i: Without Voltage Interruption
ii: With Voltage Interruption:• Slow changeover• Fast changeover
Manual Bus TransferWithout Voltage Interruption
• Involving Brief Parallel Operation
• Fault level rising
• Not used in the normal course
• In case of an emergency
Slow Changeover
• Not fault level rising
• Decay of residual voltage of motors connectedto the bus to sufficiently (about 20 per cent of therated voltage)
• Starting current inrush, heavy voltage drop
• Pre-selected number of non-essential auxiliarymotors (less than 15% drop voltage )
Fast Changeover
• Before residual motor voltage vector has fallen
• Motor speed dropped down only marginally
• Only a small rise of current
• Phase Comparison Relay
Automatic Bus Transfer
• Under Fault Condition (Voltage Drop)
• Automatic Changeover with Voltage Interruption
ATS
• The reduction of the voltage below a pre-selected value and after a pre selected timeperiod the affected incoming breaker will trip.
• After the breaker has disconnected the main thebus-tie breaker will close.
• This operation will not take place if the incomerwas tripped by any future protection device.
Return to Normal Operation(Re-Transfer)
• It shall be manually.
• Re-closing of either incoming breaker results inmomentary parallel switching of the main,followed by manually opening of the bus-tiebreaker.
• Manually opening the bus tie breaker, followedby manually closing the incoming.
0.4kV
12
3
Panel ReadyCommon Fault
50,51
5
Openor
No Service
27R
0.4kV
4
In ServiceTCS
CloseServiceNo 27i
6
7
Initial Conditions
A B
0.4kV
12
3
Panel ReadyCommon Fault
50,51
5
Openor
No Service0.4kV
4
27R
In ServiceTCS
CloseServiceNo 27i
6
7
Initial Conditions
A B
InitialConditions
Incoming AOpen or No ServiceRelay not operated
Relay
Busbar A(27R)
&
ClosePB
ClosingCoil
&Close
Command
Service PositionTCS
LocalSelectorSwitchATS
Remote
Incoming BClose & Service &Relay not operated
27i not operated
Remote
&
&
Local
ATS
0.4kV 0.4kV
Incoming A Incoming B
Bus Coupler
Opening-Trip
27R27R
1
2Both Incomings are Open
or ClosedOr no in Service.