ABB RELION 620 Series Technical Manual page 399

1MAC504801-IB E
620 series ANSI
Technical Manual
GUID-A19F9DF2-2F04-401F-AE7A-6CE55F88EB1D V2 EN
Figure 179: Thermal behavior
The required overload factor and negative sequence current heating effect factor are set by
the values of the Overload factor and Negative Seq factor settings.
In order to accurately calculate the motor thermal condition, different time constants are
used in the above equations. These time constants are employed based on different motor
running conditions, for example starting, normal or stop, and are set through the Time
constant start, Time constant normal and Time constant stop settings. Only one time
constant is valid at a time.
Table 326: Time constant and the respective phase current values
Time constant (tau) in use
Time constant start
Time constant normal
Time constant stop
The Weighting factor p setting determines the ratio of the thermal increase of the two
curves θ and θ .
A B
The thermal level at the power-up of the protection relay is defined by the Initial thermal
Val setting.
The temperature calculation is initiated from the value defined in the Initial thermal Val
setting. This is done if the protection relay is powered up or the function is disabled and
enabled back or reset through the Clear menu.
The calculated temperature of the protected object relative to the operate level, the
TEMP_RL output, is available through the monitored data view. The activation of the
BLOCK input does not affect the calculated temperature.
Protection functions
Phase current
Any current whose value is over 2.5 x I
Any current whose value is over 0.12 x I
currents are below 2.5 x I
r
All the currents whose values are below 0.12 x I
Section 4
r
and all
r
r
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