ABB RET615 Product Manual page 31

ABB
Transformer Protection and Control
RET615
Product version: 2.0
Table 30. Thermal overload protection, two time constants (T2PTTR)
Characteristic
Operation accuracy
1)
Operate time accuracy
1) Overload current > 1.2 x Operate level temperature
Table 31. Thermal overload for protection, two time constants (T2PTTR) main settings
Parameter
Temperature rise
Max temperature
Operate temperature
Weighting factor p
Short time constant
Current reference
Operation
Table 32. Transformer differential protection of two winding transformers (TR2PTDF)
Characteristic
Operation accuracy
1)2)
Operate time
Reset time
Reset ratio
Suppression of harmonics
1) Current before fault = 0.0, f
2) Includes the delay of the output contact. When differential current = 2 x set operate value and f
Function
T2PTTR
T2PTTR
T2PTTR
T2PTTR
T2PTTR
T2PTTR
T2PTTR
Low stage
High stage
= 50 Hz, results based on statistical distribution of 1000 measurements
n
Value
Depending on the frequency of the current
measured: f ±2Hz
n
Current measurement: ±1.5% of the set value
or ±0.002 x I (at currents in the range of
n
0.01...4.00 x I )
n
±2.0% of the theoretical value or ±0.50 s
Value (Range)
o
0.0...200.0 C
o
0.0...200.0 C
80.0...120.0 %
0.00...1.00
6...60000 s
0.05...4.00 x I
n
Off
On
Value
Depending on the frequency of the current
measured: f ±2Hz
n
±3.0% of the set value or ±0.002 x I
Minimum Typical
34 ms 40 ms
21 ms 22 ms
< 40 ms
Typical 0.96
DFT: -50dB at f = n x f
n
...
1MRS756891 B
Issued: 01.10.2009
Step
0.1
0.1
0.1
0.01
1
0.01
-
n
Maximum
44 ms
24 ms
, where n = 2, 3, 4, 5,
= 50 Hz.
n
31