Emerson 2202 Advanced User's Manual page 69

Parameter Parameter
Introduction
x.00 description format
Motor total
current (Pr 4.01)
as a percentage
of motor rated
2
It protection operates in this region
current
105%
70%
Rated current (Pr 5.07 or Pr 21.07) ≤ maximum Heavy Duty rating.
If the rated current is above the maximum Heavy Duty rating then Pr 4.25 can also be used to select 2 alternative protection characteristics. Both
characteristics are intended for motors where the cooling effect of the motor fan reduces with reduced motor speed, but with different speeds below
which the cooling effect is reduced. The maximum value for K is 1.01, so that above the knee of the characteristics the motor can operate
continuously up to 101% current.
Motor total
current (Pr 4.01)
as a percentage
of motor rated
2
It protection operates in this region
current
101%
70%
15%
Rated current (Pr 5.07 or Pr 21.07) >maximum Heavy Duty rating.
When the estimated temperature reaches 100% the drive takes some action depending on the setting of Pr 4.16. If Pr 4.16 is OFF(0), the drive trips
when the threshold is reached. If Pr 4.16 is On(1), the current limit is reduced to (K - 0.05) x 100% when the temperature is 100%. The current limit is
set back to the user defined level when the temperature (Pr 4.19) falls below 95%.
The time for some action to be taken by the drive from cold with constant motor current is given by:
( ) ×
T = - Pr 4.15 In 1 –
trip
Alternatively the thermal time constant can be calculated from the trip time with a given current from
-T
trip
--------------------------------------------------------- -
Pr 4.15 =
K
⎛
---------------------------- -
In 1 –
⎝
Overload
For example, if the drive should trip after supplying 150% overload (Pr 4.01) for 60 seconds with K = 1.05 then
-60
---------------------------------------- -
Pr 4.15 =
2
1.05
⎛ ⎞
---------- -
In 1 –
⎝ ⎠
1.50
The thermal model temperature accumulator is reset to zero at power-up and accumulates the temperature of the motor while the drive remains
powered-up. Each time parameter Pr 11.45 is changed to select a new motor, or the rated current defined by Pr 5.07 or Pr 21.07 (depending on the
motor selected) is altered, the accumulator is reset to zero.
Commander SK Advanced User Guide
Issue Number: 9
Keypad and Serial
display communications
Motor speed as a
50% 100%
percentage of base speed
Motor speed as a
50% 100%
percentage of base speed
2
×
K Pr 5.07
⎛ ⎞
----------------------------- -
⎝ ⎠
Pr 4.01
2
⎞
⎠
= 89
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CTSoft
RTU programming
Max. permissible
continuous
current
Pr 4.25 = 0
Pr 4.25 = 1
Max. permissible
continuous
current
Pr 4.25 = 0
Pr 4.25 = 1
Advanced parameter
Menu 0
descriptions
Menu 4
69