Electric Shaft
Group 73 Electric Shaft
The Range/Unit column in the table below shows the allowable parameter values. The text following the table explains the parameters in detail.
Parameter
Range/unit
Description
1 ELSHAFT MODE SEL
Electric shaft mode selection 2 ELSHAFT GAIN
OFF; MASTER; SLAVE
Electric shaft control gain 3 GEAR NUMERATOR
Gear scaling numerator 4 GEAR DENOMINATOR
Gear scaling denominator 5 POS ERROR LIMIT
"Position error fault limit 6 ELSH CTRL MIN SPD
0 …1000 "pos units
Electric shaft control minimum speed
1 ELSHAFT MODE SEL
Electric shaft drive mode selection. OFF
Master or Slave drive not activated for Electric Shaft control. MASTER
Drive selected to be the Master drive in Electric shaft control. Required also to set parameter 99.2. Application macro = M/F CTRL and to set 72.1 Mast/Foll mode = MASTER.
SLAVE Drive selected to be the Slave drive in Electric shaft control. Required also to set parameter 99.2. Application macro = M/F CTRL, parameter 72.1 Mast/Foll mode = FOLLOWER and 72.2 Torque selector = SPEED.
2 ELSHAFT GAIN
Electric shaft controller (P-controller) gain. Only active in Slave drive. With Elshaft Gain = 0.1 there is a -0.1% speed correction used for Slave drive if the position error (Slave signal 2.26) between Master and Slave is 1 unit.
See also section Electric shaft (73) on page 114 for the description of Electric shaft control.
3 GEAR NUMERATOR
This parameter is, together with parameter 73.4 Gear Denominator, used for giving the mechanical speed ratio between Master and Slave.
Speed ratio Master/Slave = Gear Numerator/Gear Denominator. This ratio factor is multiplied with the speed reference and position value in Slave drive only when Electric shaft control is active (On).
Example: Hoist with Master and Slave drive having equal setting for the maximum operating speed (100%) parameter 69.1 Speed scaling rpm.
Gear boxes are selected with different ratio so that full speed of Master drive corresponds to a rope speed of 3.6 m/min and full speed of Slave drive corresponds to a rope speed of 6.4 m/min; meaning we have a speed ratio = 3.6/6.4 = 0.5625 between Master and Slave.
To run the two drives together (Electric shaft control on) with the same rope speed (0 - (+/-)3.6 m/min) we should set parameter 73.3 Gear Numerator = 36 and parameter
73.4 Gear Denominator = 64 (36/64 = 0.5625). Parameter 70.1 POS SCALE should be set to same value in both
drives. NOTE: Parameter only active in Slave drive.
4 GEAR DENOMINATOR
See the description above for parameter 73.3.
5 POS ERROR LIMIT
If position error (signal 2.26) between Master and Slave drive, when Electric shaft control is on, exceeds this value, drives will trip and the Slave indicate "ELECTR SHAFT" fault. Master will then also indicate "FOLL FAULT" (Follower fault). A Reset command to Master drive will reset both drives. Unit is "pos units" (e.g. mm) according to scaling done in parameter 70.1 POS SCALE.
The parameter is only active in Slave drive.
6 ELSH CTRL MIN SPD
Electric shaft control is only active at motor speeds (without sign) above this minimum speed level. Meaning controller is inactive around zero speed e.g. during start and stop. When passing this speed limit the controllers output is gradually released respectively removed ( i.e. ramped up during start resp. ramped to zero during stop) to make a smooth change. Any accumulated position error when running below this speed limit (e.g. when motors stopped) will be controlled to zero as soon as motor is running above the minimum speed limit ELSH CTRL MIN SPD again. The parameter is only active in Slave drive.