ABB RELION REX640 Technical Manual page 1283

1MRS759142 C
REX640
Technical Manual
Dt
k
D
(
θ
∆ = ⋅
h n 1
( ) k
( )
τ
⋅
22 w
GUID-C2B4D3D0-4D65-4DBC-B80B-A8B066450FA0 V1 EN
Dt
D
θ
∆ =
h 2 n
( )
1

 

τ
⋅
  
k

22
 

GUID-DFF18659-9626-4C67-8C44-A549C62B0903 V1 EN
Where
Δθ
hr
The constants Շ
, k , k
w 21 22
are obtained from the Load factor calculation and parameter selection module.
The rated hot-spot to top oil gradient, HS_TOIL_GRA (Δθ
formula as shown in the
Hotspot Tmp rise Top oil Tmp rise
θ
∆ =
hr
Current type test
 

I
rated

GUID-986A5BB5-544F-4397-AE77-92AED9EA5E4B V1 EN
Where
I
rated
Hotspot Tmp rise
Top oil Tmp rise
Current type test
th
At each time step, the n
value; the solutions of which are combined in accordance with the hot-spot
temperature rise equation.
D
θ θ θ
∆ = ∆ + ∆
h n 1 h n 1 1 h n 1
( ) ( )
−
GUID-4AE4422A-637E-428C-8B8C-3AAB68CF511D V1 EN
D
θ θ θ
∆ = ∆ + ∆
h 2 n h 2 n 1 h
( ) ( − )
GUID-0D6351C9-4A60-4767-94E7-B9AFB0510EFA V1 EN
The initial conditions are calculated by setting the time derivative equal to zero in
D∆θ and D∆θ equations, resulting in the following equations.
h1(n) h2(n)
Condition monitoring functions
y
K
)
θ θ
⋅ ∆ ⋅ − ∆
hr
h n 1 1
21
( − )
y
k
1 K
( θ
( )
⋅ − ⋅ ∆ ⋅ − ∆
hr
21


o



Hot-spot-to-top-oil gradient at rated current [°C]
and y are varying according to the Cooling mode setting and
Equation 293.
−
y



Rated current of the transformer
Hot-spot temperature rise over ambient at rated load
Top oil temperature rise over ambient at rated load
Current applied in type testing to reach rated hot-spot temperature
value of DΔθ and DΔθ
h1(n)
( )
2 n
( )
Section 7
θ )
h 2 n 1
( ( − )
), is calculated using the
hr
are calculated from the (n-1)
h2(n)
(Equation 291)
(Equation 292)
(Equation 293)
(Equation 294)
(Equation 295)
1277