T
SRamp1
= 2 √(Δw / J
Max
) = 2 √(5.0 / 32.3) = 0.78s
For RFC-A mode the general equations are used in the same way as for Open-loop mode. The required values are calculated as follows:
Δw = 1000 / ramp rate
a
Max
= 1000 / ramp rate
J
Max
= 1000 / MaxRateOfChangeOfAcceleration (02.007)
Parameter 02.008 Standard Ramp Voltage
Short description Defines the standard ramp voltage used by the ramp system
Mode Open‑loop
Minimum −VM_DC_VOLTAGE_SET Maximum VM_DC_VOLTAGE_SET
Default See exceptions below Units V
Type 16 Bit User Save Update Rate Background read
Display Format Standard Decimal Places 0
Coding RW, VM, RA
Voltage Region Default Value
110V All 375
200V All 375
400V 50Hz 750
400V 60Hz 775
575V All 895
690V All 1075
See RampModeSelect (02.004).
Parameter 02.009 Deceleration Fail Detection Disable
Short description Set to 1 to disable the deceleration fail detection function
Mode Open‑loop
Minimum 0 Maximum 1
Default 0 Units
Type 1 Bit User Save Update Rate Background read
Display Format Standard Decimal Places 0
Coding RW
In the following circumstances it is possible that the motor may not decelerated or even accelerate.
1. When standard ramp is selected with a high inductance supply it is possible for the d.c. bus voltage to rise as the motor speed approaches
zero, and so the motor will continue to rotate slowly and not stop.
2. An overhauling load can cause the motor to accelerate.
It can be a problem if the drive state is changed to the "Decelerating" state and the motor does not stop. If DecelerationFailDetectionDisable
(02.009) is at its default value of 0, the motor frequency or speed is monitored in the "Decelerating" state, and if this does not fall over a period of 10s
the ramp output is forced to zero and the drive state is changed to "Stop" or "Inhibit" as appropriate.
If DecelerationFailDetectionDisable (02.009) = 1 this feature is disabled. This can be used in the following circumstances to prevent the system state
from changing from the "Decelerating" state before the motor has stopped:
1. If S ramps are being used with long ramp rates, and the motor is still accelerating when the drive is changed to the "Decelerating" state
because the run command is removed, then the ramp output may increase further before falling again towards zero.
2. The speed may appear not to reduce when very long ramp rates are used.
Parameter 02.010 Acceleration Rate Selector
Short description Defines which acceleration rate is used by the ramp system
Mode Open‑loop
Minimum 0 Maximum 9
Default 0 Units
Type 8 Bit User Save Update Rate 16ms
Display Format Standard Decimal Places 0
Coding RW
The AccelerationRateSelector (02.010) is used to either select an acceleration rate directly or to define the method used to select an acceleration rate.
If 1 ≤ AccelerationRateSelector (02.010) ≤ 8 the acceleration rate is selected directly, i.e. 1 selects AccelerationRate1 (02.011), 2
selects AccelerationRate2 (02.012), etc. If AccelerationRateSelector (02.010) = 0 the acceleration rate is selected with the acceleration rate select
bits as shown in the table below.
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