06 SEP674 RET670 Thermal Overload Protection
Transcript of 06 SEP674 RET670 Thermal Overload Protection
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1MRG019264
Transformer protection RET670Thermal overload protection
Substation Automation Products
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 3
Application thermal overload protection
Temporary overloading necessary in stressedsituations
Not possible to design the system to manageall situations
Temporary overload not harmful
Hard decision for operator to disconnect thetransformer
Consequences of overload
Degrading in the quality of the transformer oil
Forced aging of insulation
Increase risk of internal faults
Hot spots within the transformer
Degrade paper insulation
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 4
Based on measuring the true RMScurrent
Uses the largest phase current tocalculate the heat content
Two time constants (i.e. ONAN or OFAF)
Possibility to adjust the time constants athigh and/or low currents
Binary inputs to
select time constant
change reference settings
empty heat content
block the function
Thermal overload protection Application
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 5
SMAI
TR PTTR
49 Ith
SMAI
SMAIΣ
SMAI
TR PTTR
49 Ith
TR PTTR
49 Ith
Thermal overload protection Application
Number of instances: Customized: 0 – 6
Pre-configured:
Included: 1
Optional: < 1
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 6
The relative final temperature (heatcontent) is expressed as:
The actual temperature (heat content) iscalculated as:
if (heating)
or:
if (cooling)
HEATCON> ALARM1 Alarm> ALARM2 Alarm
> ITrip Trip
I_MEASURE I > ITrip Start
Monitored data
Analog Binary
HEATCON
Operating characteristicsThermal overload protection
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 7
Present time to operation is calculated as:
The time to lockout release is calculatedas:
TTRIP If Start
Monitored data
Analog Binary
If TTRIP < Warning WARNING
TRESLO If Trip
Operating characteristicsThermal overload protection
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 8
t[min]
Θ[%]
ResetLockoutTemp
Tau 1
Alarm 1 Alarm 2
~ IRef
WARNING
ResLo
~ ITrip
100%
~ IBase 1
Current step
START/RESET
TRIP and
LOCKOUT
TripTemp
Estimated time to trip
Estimated time to reset
TTRIP
TRESLO
Rated power
ThetaInit
Operating characteristicsThermal overload protection
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 9
Final temp >
Trip Temp
Actual Temp >
Alarm X Temp
Calc of final
temp
Calc of heat
content
Actual Temp >
Trip Temp
Actual Temp
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 10
First instance ofTR PTTR
Thermal overload protection settingsOverview
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 12
Base current 1
Time constant 1
Rescaling of Tc if I >
Rescaling percentage
Rescaling of Tc if I <
Rescaling percentage
Cooling input low
Thermal overload protection settingsTime constant 1
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 13
Cooling input high
Base current 2
Time constant 2
Rescaling of tc if I >
Rescaling percentage
Rescaling of tc if I <
Rescaling percentage
Thermal overload protection settingsTime constant 2
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 14
Trip and supervision
Steady state trip level
Alarm 1 – level warning
Alarm 2 – level warning
Lockout reset level
Warning – time to trip
Thermal overload protection settingsTrip and supervision
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 15
Test/Functions status/Currentprotection/ThermalOverload2TimeConst (PTTR,49)
TRIP
START
ALARM1
ALARM2
LOCKOUT
WARNING
Monitored dataThermal overload protection
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© ABB GroupSeptember 10, 2015 | Slide 16
Test/Functions status/Currentprotection/ThermalOverload2TimeConst(PTTR,49)
I-MEASURE Measured current (% ofrated current)
HEATCONT – Heat content of thetransformer (%)
TTRIP – Estimated time to trip (min)
TRESLO – Estimated time to reset (min)
TTRIPCAL – Time status to trip
0: Not active
1: Long time
2: Active
TRESCAL – Time status to reset
0, 1 or 2
Monitored dataThermal overload protection
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Chapter 06
© ABB GroupSeptember 10, 2015 | Slide 17© SA-T TrainingSeptember 10, 2015 | Slide 17