Standard Ramp Voltage - Emerson unidrive sp User Manual

Parameter Keypad and
Menu 2
structure display
Programmed
ramp rate
S ramp
acceleration
ramp
T/2 T/2
T
The time taken in seconds for the ramp output to change by frequency (Δf*) or speed (Δw*) is given below. Two cases are given because the total
ramp time must be calculated with a different equation depending on whether the acceleration is able to reach the selected ramp rate (A) or not. If the
required change is small the selected ramp rate is not reached and the ramp does not include the central linear ramp region. If the required change is
larger the ramp does include the central linear region as shown in the diagram above.
Frequency (Open-loop mode)
2
Δf*
= 100 x J / A
linear
where:
A is the selected ramp rate in s / 100Hz
J is parameter Pr 2.07, the S ramp acceleration limit in s
If the required change is less than Δf*
= 2 √ (Δf* x J / 100)
T
Ramp1
T = (Δf* x A / 100) + (J / A)
Ramp2
Speed (Closed-loop vector and servo)
2
Δw*
= 1000 x J / A
linear
where:
A is the selected ramp rate in s / 1000rpm
J is Pr 2.07, the S ramp acceleration limit in s
If the required change is less than Δw*
used.
= 2 √ (Δw* x J / 1000)
T
Ramp1
T = (Δw* x A / 1000) + (J / A)
Ramp2
The default values for the ramp rate and S ramp acceleration limit have been chosen such that for the default maximum speed, the curved parts of the
S ramp are 25% of the original ramp if S ramp is enabled. Therefore the ramp time is increased by a factor of 1.5.
2.08

Standard ramp voltage

Drive modes Open-loop, Closed-loop vector, Servo
Bit SP
Coding
Range Open-loop, Closed-loop vector, Servo
Default Open-loop, Closed-loop vector, Servo
Update rate Background read
This voltage is used as the control level for standard ramp mode. If this parameter is set too low the machine will coast to rest, and if it is set too high
and no braking resistor is used the drive may give an OU trip. The minimum level should be greater than the voltage produced on the DC bus by the
highest supply voltage. Normally the DC bus voltage will be approximately the rms supply line voltage x √2.
46
Parameter Parameter
x.00 description format
Demanded Speed
Acceleration
Actual Speed
T/2 T/2 t
T
2
/ 100Hz
should be used, but if the speed change is greater or equal to Δf*
then T
linear Ramp1
2
/ 1000rpm
should be used, but if the speed change is greater or equal to Δw*
then T
linear Ramp1
FI DE Txt VM DP ND RA NC NV
1
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Advanced parameter
Macros
descriptions
PT US RW BU
1 1
0 to DC_VOLTAGE_SET_MAX V
200V rating drive: 375
400V rating drive: EUR: 750 / USA: 775
575V rating drive: 895
690V rating drive: 1,075
Serial comms Electronic
Performance
protocol nameplate
linear
linear
PS
1 1
Unidrive SP Advanced User Guide
RFC mode
T should be used.
Ramp2
T should be
Ramp1
Issue Number: 10