Lenze i510 Series Commissioning

8.3.4 Slip compensaon
In case of a load, the speed of an asynchronous motor decreases. This load-dependent speed
drop is called slip. The slip compensaon serves to counteract the load-dependent speed loss.
Precondions
The funcon is only eecve in the motor control type "V/f characterisc control (VFC open
loop)".
In order that the funcon can determine the rated slip correctly, the following parameters
must be set correctly:
•
Rated speed
•
Rated frequency
•
Number of pole pairs (Automacally calculated from Rated speed and Rated frequency)
Details
The slip compensaon increases or decreases the output frequency as a response to a load
change. Thus, the slip is counteracted and the speed is kept precisely.
Output frequency
Load
Motor speed
The rated slip required for the slip compensaon is calculated by the inverter according to the
following formula:
Rated slip [%] = (1 - (rated motor speed [rpm] / (120 * rated motor frequency [Hz] / number of
poles))) * 100
Calculaon example:
•
Rated motor speed = 1750 rpm
•
Rated motor frequency = 60 Hz
•
Number of poles = 2 * Number of pole pairs = 2 * 2 = 4
•
Rated slip = (1 - (1750 / (120 * 60 / 4))) * 100 = 2.77 %
The rated slip represents the reducon of the motor speed due to the motor load. At full
speed and full load, the motor given in the example would rotate with 1750 rpm, which
means 2.77 % below its synchronous speed of 1800 rpm. In order to compensate this speed
loss, the inverter increases the output frequency by the rated slip mulplied by the rated
motor frequency. In the example 2.77 % * 60 Hz = 1.66 Hz increase at full load.
In order to consider load changes, the inuence of the rated slip on output frequency can be
adapted in 0x2B09:001 (P315.01). A seng of 100 % corresponds to the rated slip of the
machine in the nominal operang point.
With reference to the example above and a setpoint frequency of 60 Hz:
•
If 0x2B09:001 (P315.01) = 100 %, the output frequency is = 61.66 Hz
(60 Hz + 100 % * 1.66 Hz).
•
If 0x2B09:001 (P315.01) = 50 %, the output frequency is = 60.83 Hz
(60 Hz + 50 % * 1.66 Hz).
Addionally, the lter me for the slip compensaon can be adapted in 0x2B09:002 (P315.02)
if required. The preset lter me is adapted to typical motors. If full load or nearly full load
oscillaons or instabilies occur, we recommend an increase of the lter me.
Parameter Name / value range / [default seng] Info
0x2B09:001
(P315.01)
Slip compensaon: Gain
(Slip compens.: Slip: gain)
-200.00 ... [100.00] ... 200.00 %
Adjustment in percent of the slip calculated.
•
For instance required for deviaons of the real motor data from the
nameplate data.
•
A seng of 100 % corresponds to the rated slip of the machine in the
nominal operang point.
0x2B09:002
(P315.02)
Slip compensaon: Filter me
(Slip compens.: Filter me)
1 ... [100] ... 6000 ms
Filter me for the slip compensaon.
•
The preset lter me is adapted to typical motors.
Motor control
Opmisaon of motor control
Slip compensaon
135

Lenze i510 Series Specifications

General

Protection Class	IP20
Overload Capacity	150% for 60 seconds
Enclosure Rating	IP20
Dimensions	Varies by model
Weight	Varies by model
Control Type	V/f control, vector control
Communication Interfaces	CANopen, Modbus RTU, EtherCAT, PROFIBUS, PROFINET
Ambient Temperature	-10°C to +50°C
Braking Resistor	Optional
Safety	STO (Safe Torque Off)
Protection Features	Overcurrent, overvoltage, undervoltage, overtemperature, short circuit
Output Voltage	0 to input voltage
Input Voltage	200-240 V, 380-480 V
Voltage Range	200-240 V, 380-480 V
Frequency Range	0 to 599 Hz