Monitored Data; Operation Principle - ABB RET650 Technical Manual

1MRK 504 135-UEN A
8.5.6
8.5.7
Technical manual

Monitored data

Table 95: TRPTTR Monitored data
Name Type
TTRIP REAL
TTRIPCAL INTEGER
TRESCAL INTEGER
TRESLO REAL
HEATCONT REAL
I-MEASUR REAL

Operation principle

The sampled analogue phase currents are pre-processed and for each phase current the
true RMS value of each phase current is derived. These phase current values are fed
to the Thermal overload protection, two time constants (TRPTTR).
From the largest of the three phase currents a relative final temperature (heat content)
is calculated according to the expression:
2
æ ö
I
Q = ç
÷
ç ÷
final
I
è ø
ref
EQUATION1171 V1 EN
where:
I
I
ref
If this calculated relative temperature is larger than the relative temperature level
corresponding to the set operate (trip) current a start output signal START is activated.
The actual temperature at the actual execution cycle is calculated as:
Values (Range) Unit
- -
- -
- -
- -
- %
- %
is the largest phase current
is a given reference current
Section 8
Current protection
Description
Estimated time to trip (in
min)
Calculated time status to
trip: not active/long time/
active
Calculated time status to
reset: not active/long
time/active
Estimated time to reset of
the function (in min)
Percentage of the heat
content of the
transformer
Current measured by the
function in % of the rated
current
(Equation 49)
175