Standard user guide
V51-00-V19 eng
-17-
Rights to changes reserved
2.8
Information about positions tolerance and hysteresis (PAR. U and Y)
(Not available in program no. 0)
The purpose with parameter U is to tell the inverter how accurate the positioning should be. If the ramps
(acceleration /deceleration) were set too high would it result in problems with finding the right position
precisely.
Sample:
PARAMETER U
= 3 (Positions tolerance)
PARAMETER Y
= 4 (Hysteresis area)
If the present position is 200 and the wanted position is 1000 happens as follows: The motor starts
accelerating with the set up acceleration until et reaches the max frequency. The inverter calculates when
to begin to decelerate to hit the right position. When the wanted position is reached (± 3 positions) is the
DC brake activated. And the output is set to 0 Hz.
When the wanted position is reached is the hysteresis area activated. This means that the motor frequency
is 0 Hz in all the shaded area on fig. 6. Only if the position is forced outside the area is a new positioning
against the wanted position made.
Position
Position
Wanted position = 1000
Positions tolerance
Outside positions tolerance
Outside positions tolerance
1003
1000
997
3
3
Figur 5
Wanted position
Position tolerance
Motor OFF
Outside Hyst. area
Outside Hyst. area
Hyst. Area
Hyst. Area
3
3
4
4
1007
993
Fig 6