Advanced Power technologies TTC-1000, Instruction & Operation Manual

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V6.230 20131017
40
The steady state winding temperature is calculated based on the following
equation
1
:
TO
m
n n n n
g HS
RatedLoad CRatio Load fl)
n
  
  
2
) / * ( *
( [1]
Where: n = 1, 2, 3
perature windng tem alculated Ultimate c
n
HS


load e at rated temperatur r Top Oil ise #n ove Hot Spot R
g

fl) (
n

nt #n load curre Measured Load
n

ratio CT Primary CTRatio
n n

current d of #n CT Rated loa Load Rated
n

cooling other all for 0.8 FOW, or FOA directed for 1.0 m

emperature Top Oil T
TO
Measured Probe First
 
It is noted that the Hot Spot Rise over Top Oil at rated load is not always
available. In this case we recommend using a value between 18 to 22 ºC.
To accommodate the transient affect of changing load current, the winding
temperature can be estimated at any point in time by entering the winding time
constant. Therefore, the displayed winding temperature is calculated as follows:
TO
t
HS HS HS
HS
I U
e t
   

   

) 1 )( ( ) (
/
[2]
Where:
e t e at tim temperatur Winding (t)
θ
HS

above [1] equation using e temperatur winding Ultimate
θ
U
HS

[1] equation using emperature winding t Initial
θ
I
HS

minutes in constant time Winding
HS
 
re temperatu top oil Measured
θ
TO

Because data to calculate

W
may not be available, the recommended setting for
the winding time constant is between 5 to 10 minutes.
The TTC-1000 also equipped with a feature to run the winding temperature
calculation from a redundant top oil probe should the primary top oil probe fail.
See Section
4.5.1 about naming temperature probes.
1
ANSI C57.91-1995