Product Description:
Electronic Soft Starters
Soft starting and soft stopping of three-phase induction motors at powers up to 800 kW
Applications
Pumps
Fans and compressors
Conveyor belts
Grinding machines, saws
Fast and heavy-duty conveyor systems
Drives using pole-change motors
Machines with gearbox, belt or chain drives
User benefits
Mechanical
Reduced cost of transmission components
Low starting torque
Starting torque adjustable to requirement
Reduced maintenance costs
Low starting torque reduces belt slip
Lower repair cost
Fatigue effects reduced (Star/delta, transformer and single-phase starting cause high torque peaks)
Machine protection
Electronic overload trip (with OPTION LS-I1)
Electrical
Low starting current
Advantages compared with star/delta
Low maintenance costs
Low-loading of contactor contacts with zero-current switching
Only two voltage ranges
3AC 110...500 ±10% V
3AC 220...690 ±10% V
Features
An external bridging contactor can be used to reduce losses
Shutdown on detection of phase failure during ramp up
Can be combined with electronic d.c. injection brake (refer to technical manual LEKTROMIK B4)
OPTION LS-I1 provides for:
Current limit during ramp-up with switch-on pulse, monitoring of power with overload trip (stall protection), power factor improvement at low load special circuit to damp drive oscillation (e.g. with pumps), energy saving circuit for lightly loaded drives
OPTION LS-I2 provides for:
Current limit during ramp-up, start monitoring, optimised operation with pumps
OPTION LS-N provides for:
Closed-loop speed control for load-independent starting, operation for pumps
Principle of operation
The following alternative LEKTROMIK soft starters can be supplied:
S2 in the conventional standard connection in series with the motor
SD2 connected within the delta motor winding
Advantage:
high motor power for same soft-start current
The modes of operation "Soft Start" and "Soft Stop" make use of thyristors in a fully controlled connection. The three thyristor pairs vary the voltage applied to the motor using phase control. The torque of the motor can be varied over a wide range. The motor voltage increases as ramp function during soft start.The starting voltage ( = switch-on voltage) and the inclination ( = acceleration) are adjustable within a wide range. A monitoring signal "End of Ramp" indicates the end of ramp up. With soft stop operation the voltage can be reduced to zero as a ramp function. This can prevent a load with a large frictional component from stopping too abruptly.The main contactor is opened with zero current on completion of ramp down. This provides a considerable increase in the life of the main contactor.
View All
