Control Techniques Digitax ST Advanced User's Manual page 106

Parameter
Menu 7
structure
7.28 T7 analog input 2 current loop loss
7.29 T8 analog input 3 current loop loss
Bit SP
Coding
1
Update rate Background write
If an analog input is used with 4-20mA or 20-4mA current loop modes the respective bit (Pr 7.28 - analog input 2 and Pr 7.29 -analog input 3) is set to
one if the current falls below 3mA. If the current is above 3mA with these modes or another mode is selected the respective bit is set to zero.
7.30 T5/6 analog input 1 offset
Bit SP
Coding
Range ±100.00 %
Default 0.00
Update rate Background read
7.31 T7 analog input 2 offset
7.32 T8 analog input 3 offset
Bit SP FI
Coding
Range ±100.0 %
Default 0.0
Update rate Background read
An offset can be added to each analog input with a range from -100% to 100%. If the sum of the input and the offset exceeds ±100% the results is
limited to ±100%.
7.33 T9 analog output 1 control
Bit SP
Coding
Range 0 to 2
Default 2
Update rate Background read
This offers a simple control of Pr 7.19 to change the source for the analog output for use from Menu 0. When this parameter is set to 0 or 1 the drive
constantly writes Pr 5.01 or Pr 4.02 to Pr 7.19 respectively.
Parameter value Parameter string
0
1
2
7.34 IGBT junction temperature
Bit SP
Coding
Range ±200 °C
Update rate Background write
The IGBT junction temperature displayed in this parameter is the sum of the power circuit 1 temperature (Pr 7.04) and a thermal model of the drive
power stage.
Pr 7.34 gives the IGBT junction temperature that would be produced after the delay taken to trip the drive or reduce the switching frequency if the
drive output current was increased to its maximum level. This means that Pr 7.34 may always show a temperature that is higher than the power circuit
1 temperature even when the drive is disabled. If the calculated IGBT temperature exceeds the levels shown in the table below the switching
frequency is reduced provided this feature has not been disabled (by setting Pr 5.35 to 1) or the minimum switching frequency has not been reached.
The switching frequency can be reduced from 12kHz to 6kHz to 3kHz, or from 8kHz to 4kHz. If this feature has been disabled (i.e. Pr 5.35 is one) or
the minimum switching frequency is reached the drive initiates an Oht1 trip. Once the switching frequency has been reduced the drive determines
when the switching frequency can be switched back up again.
106
Keypad and
Parameter x.00
display
FI DE Txt VM DP ND
1
FI DE Txt VM DP ND
2
DE Txt VM DP ND
1
FI DE Txt VM DP ND
1
Action
Fr Write Pr 7.19 = Pr 5.01
Ld Write Pr 7.19 = Pr 4.02
AdV No action
FI DE Txt VM DP ND
1
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Parameter Advanced parameter
description format descriptions
RA NC NV PT US RW BU
1 1
RA NC NV PT US RW BU
1 1
RA NC NV PT US RW BU
1 1
RA NC NV PT US RW BU
1 1
RA NC NV PT US RW BU
1 1
Serial comms Electronic
protocol nameplate
PS
PS
PS
PS
1
PS
Digitax ST Advanced User Guide
Issue Number: 1
Performance