5.19
Date Code 20130214 Instruction Manual SEL-2414 Transformer Monitor
Metering and Monitoring
Monitoring
The equivalent life at the reference hot-spot temperature (95ºC or 110ºC) that
will be consumed in a given time period for a given temperature cycle is
. Equation 5.10
During 24 hours, the total number of time intervals is
Equation 5.11
Because the time intervals and the total time period used in the thermal model
will be constant, we can simplify the calculation of F
EQA
to the following.
Equation 5.12
Total Accumulated Loss of Life
The device estimates the total accumulated loss of insulation life in percentage of
normal insulation life by summing all of the daily RLOL values.
Equation 5.13
The device stores the TLOL value at midnight each day. You can use the THE P
command to load an initial value of TLOL into the device.
where:
F
EQA
= equivalent insulation aging factor for a 24-hour time
period
n = index of the time interval, Δt
N = total number of time intervals for the 24-hour time period
F
AAn
= insulation aging acceleration factor for the time interval,
Δt
n
Δt = time interval (fixed at 1 minute)
where:
Δt = time interval (fixed at 1 minute)
F
EQA
F
AA
n
n1=
N
∑
Δt
n
•
Δt
n
n1=
N
∑
--------------------------------------=
N
24
Δt
60
------
⎝⎠
⎛⎞
-----------
1440
Δt
------------==
F
EQA
F
AA
n
n1=
1440
∑
1440
-----------------------=
where:
TLOL
d
= total accumulated loss of life for the present period (day)
RLOL
d
= most recent daily calculation
TLOL
d–1
= previous TLOL (from yesterday)
To Next Page
Loading...
