ABB Relion 611 Series, Technical Manual

Page: 153 / 536

Table 142: Modification of internal FLC
Ambient Temperature T
amb
Internal FLC
<20°C FLC x 1.09
20 to <40°C FLC x (1.18 - T
amb
x 0.09/20)
40°C FLC
>40 to 65°C FLC x (1 –[(T
amb
-40)/100])
>65°C FLC x 0.75
The ambient temperature is used for calculating thermal level and it is available in the
monitored data view from the
TEMP_AMB
output. The activation of the
BLOCK
input
does not affect the
TEMP_AMB
output.
The Env temperature Set setting is used:
• If the ambient temperature measurement value is not connected to the
AMB_TEMP input in ACT.
• When the ambient temperature measurement connected to 49M is set to "Not in
use" in the RTD function.
• In case of any errors or malfunctioning in the RTD output.
Thermal level calculator
The module calculates the thermal load considering the TRMS and negative-sequence
currents. The heating up of the motor is determined by the square value of the load
current.
However, in case of unbalanced phase currents, the negative-sequence current also
causes additional heating. By deploying a protection based on both current
components, abnormal heating of the motor is avoided.
The thermal load is calculated based on different situations or operations and it also
depends on the phase current level. The equations used for the heating calculations
are:
θ
τ
B
r r
t
I
k I
K
I
k I
e p
=
×





 +
×
×














× −
( )
×
−
2
2
2
2
1
/
%
GUID-526B455A-67DD-46E7-813D-A64EC619F6D7 V2 EN
(Equation 6)
θ
τ
A
r r
t
I
k I
K
I
k I
e
=
×





 +
×
×














× −
( )
×
−
2
2
2
2
1 100
/
%
GUID-9C893D3E-7CAF-4EA6-B92D-C914288D7CFC V2 EN
(Equation 7)
1MRS757454 D
Section 4
Protection functions
611 series 147
Technical Manual