Detailed transformer protection concepts and with numerical calculation.Description complète
Detailed transformer protection concepts and with numerical calculation.Full description
power transformer protection
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The transformer is an essential part of the transmission and appropriation framework. The point of creating, transformer security structure is to oversee in such a manner, that we are utilizing microcontroller and IoT to give programmed security and
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Power Transformer Protection
Descripción: ABB Transformer Protection
Question on Transformer.Full description
Generator & transformer protection for 600MW class generator
Presentation on Power Transformer & Distribution Transformer Protection
Calculations for Design Parameters of Transformer
Protection scheme required for the protection of power system components against abnormal conditions such as faults etc., and that essentially consists of protective relaying and circuit breaker. Protective relay senses the fault and determines the l
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transformer
Descripción: power transformer
transformerFull description
Transformer Protection
SLIDE 1
SLIDE 2
SLIDE 3
Maximum fuse fuse rating maximum rating or or circuit breaker circuit breaker setting setting 125% of full 125% of full load current load current
480 240/120V
Set 2.5 I fl set ≤≤2·5I fl
set Set≤≤1·25I 1.25fl I fl
SLIDE 4
SLIDE 5
fuse rating < 2·5Ifl
SI
Relay set < 3Ifl
SLIDE 6
Differential Protection
r
r
y
y
b
b
R
Y
SLIDE 7
B
When applying relays for the protection of transformers, the following points must be considered: • Line currents present on either side of star delta transformers will differ in magnitude and/or phase. • Any sudden change in the energisation of the transformer will produce an inrush magnetising current into or out of one winding. This can occur when energising a previously disconnected transformer or when a sudden appreciable drop in transformer load occurs. • Delta connected windings do not provide a path for zero sequence currents during earth fault conditions. • Tap changers used for voltage regulation purposes cause the turns ratio and hence the voltage and current magnitudes to vary. SLIDE 8
Magnetising Inrush for a Small Transformer
SLIDE 9
Generator
Relay point 1 1 0
Relay point 2
Relay point 1
1
0
1
1
Fault current flow in transformers
SLIDE 10
External fault Stability
Internal fault Operation SLIDE 11
Internal Fault:
Operation of relay
External fault: maloperation of relay Consider and modify connections for correct operation
Current Transformer Connections and Secondary Current Flow SLIDE 12
Operating current I2 (pu) 10 Bias Setting
9 8
40% 7 6 30%
5 4 20% 3 2 1
2
4
6
8
10
Bias current I1 (pu)
SLIDE 13
12
14
16
18
20
SLIDE 14
Schematic of 1-pole of differential relay system Transformer
Bias coil
Harmonic bias coil
Operating coil
SLIDE 15
Star-Delta-Star Station Transformer
250 / 1
132 kV 30MVA 11 kV
SLIDE 16
2500 / 1
2I
3I
I
I
I
3I I
I
I
Winding arrangement & current distribution SLIDE 17
C.T. Connections
O.C. Relays
SLIDE 18
SLIDE 19
High impedance differential (Principle of operation)
A
B RACT
RLA
RLB If
RR
ZEA
RBCT
ZEB
Vf 87
IR
Saturation has the effect of lowering the excitation impedance and is deemed to have taken place in CT B until, at the limit, the shunt impedance becomes zero and the CT has no output. Vf = If (RLB + RB CT) Current through relay IR = Vf / (RR + RLB + RB CT) If RR is small IR ≈ If which is not acceptable If RR is large IR is reduced and without incurring significant error IR =
(R +R ) Vf = If . LB B CT RR RR
IR can be reduced below any specified relay setting SLIDE 20
SLIDE 21
SLIDE 22
Percentage of Transformer Winding Protected Against Earth Faults