Parameter
structure
Keypad and
display
Parameter x.00
Parameter description
format
Advanced parameter
descriptions
Serial comms
protocol
Electronic
nameplate
Performance
16 Digitax ST Advanced User Guide
www.controltechniques.com Issue Number: 1
4.1 Parameter ranges and variable maximums:
The two values provided define the minimum and maximum values for
the given parameter. In some cases the parameter range is variable and
dependant on either:
• other parameters,
• the drive rating,
• or a combination of these.
The values given in Table 4-1 are the variable maximums used in the
drive.
Table 4-1 Definition of parameter ranges & variable maximums
Maximum Definition
SPEED_FREQ_MAX
[40000.0rpm]
Maximum speed reference
If Pr 1.08 = 0: SPEED_FREQ_MAX = Pr 1.06
If Pr 1.08 = 1: SPEED_FREQ_MAX is Pr 1.06 or – Pr 1.07 whichever is the largest
(If the second motor map is selected Pr 21.01 is used instead of Pr 1.06 and Pr 21.02 instead of Pr 1.07)
SPEED_LIMIT_MAX
[40000.0rpm]
Maximum applied to speed reference limits
A maximum limit may be applied to the speed reference to prevent the nominal encoder frequency from
exceeding 500kHz. The maximum is defined by
SPEED_LIMIT_MAX (in rpm) = 500kHz x 60 / ELPR = 3.0 x 10
7
/ ELPR subject to an absolute maximum of
40,000 rpm.
ELPR is equivalent encoder lines per revolution and is the number of lines that would be produced by a
quadrature encoder.
Quadrature encoder ELPR = number of lines per revolution
F and D encoder ELPR = number of lines per revolution / 2
Resolver ELPR = resolution / 4
SINCOS encoder ELPR = number of sine waves per revolution
Serial comms encoder ELPR = resolution / 4
This maximum is defined by the device selected with the speed feedback selector (Pr 3.26) and the ELPR set
for the position feedback device.
SPEED_MAX
[40000.0rpm]
Maximum speed
This maximum is used for some speed related parameters in menu 3. To allow headroom for overshoot etc. the
maximum speed is twice the maximum speed reference.
SPEED_MAX = 2 x SPEED_FREQ_MAX
DRIVE_CURRENT_MAX
[9999.99A]
Maximum drive current
The maximum drive current is the current at the over current trip level and is given by:
DRIVE_CURRENT_MAX = K
C
/ 0.45
AC_VOLTAGE_SET_MAX
[690V]
Maximum output voltage set-point
Defines the maximum motor voltage that can be selected.
200V drives: 240V, 400V drives: 480V
AC_VOLTAGE_MAX
[930V]
Maximum AC output voltage
This maximum has been chosen to allow for maximum AC voltage that can be produced by the drive including
quasi-square wave operation as follows:
AC_VOLTAGE_MAX = 0.78 x DC_VOLTAGE_MAX
200V drives: 325V, 400V drives: 650V
DC_VOLTAGE_SET_MAX
[1150V]
Maximum DC voltage set-point
200V rating drive: 0 to 400V, 400V rating drive: 0 to 800V
DC_VOLTAGE_MAX
[1190V]
Maximum DC bus voltage
The maximum measurable DC bus voltage.
200V drives: 415V, 400V drives: 830V
MOTOR1_CURRENT_LIMIT_MAX
[1000.0%]
Maximum current limit setting for motor map 1
The maximum current limit setting is the maximum applied to the current limit parameters in motor map 1.
Where:
The Maximum current is (1.75 x
K
C
).
Motor rated current is given by Pr 5.07
MOTOR2_CURRENT_LIMIT_MAX
[1000.0%]
Maximum current limit settings for motor map 2
This maximum current limit setting is the maximum applied to the current limit parameters in motor map 2.
The formulae for MOTOR2_CURRENT_LIMIT_MAX are the same for MOTOR1_CURRENT_LIMIT_MAX
except that Pr 5.07 is replaced with Pr 21.07 and Pr 5.10 is replaced with Pr 21.10.
Maximum
current limit
=
[
Maximum current
]
x 100%
Motor rated current
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