ABB 615 series Technical Manual page 306

Section 4
Protection functions
300
Table 308: Modification of internal FLC
Ambient Temperature T
amb
<20°C
20 to <40°C
40°C
>40 to 65°C
>65°C
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:
2

I
  
 K
θ =  + ×
 
B 2
k I k I
×

 r  

GUID-526B455A-67DD-46E7-813D-A64EC619F6D7 V2 EN
2

I
  

K
θ =  + ×
 
A 2
k I k I
 ×
r
  

GUID-9C893D3E-7CAF-4EA6-B92D-C914288D7CFC V2 EN
Internal FLC
FLC x 1.09
FLC x (1.18 - T
FLC
FLC x (1 –[(T
FLC x 0.75
2

I

t /
2
− τ
( )
 1 e p %
× − ×

×

r 

2

I

t /
2
− τ
( )
 1 100 %
e
× − ×

× 
r


1MAC059074-MB A
x 0.09/20)
amb
-40)/100])
amb
(Equation 16)
(Equation 17)
615 series ANSI
Technical Manual