Tag: dc converter

A soft starter is an electronic motor control device for the soft start and stop of three-phase induction motors. The motor voltage is adjusted with a phase control by a ramp function. The supply frequency of the motor remains identical to the mains frequency. With soft starting, the initial voltage (= starting torque) and the voltage rise (= acceleration) are adjustable. During soft stop, the voltage is reduced with a ramp function.

Applications:
* Speed control e.g. of fans and blowers 
* Motor starting – conservation of resources

Start attentuation (AM) and soft starters (SM, SM2)
0,5 – 7,5 kW

Soft start and soft stop LEKTROMIK^®S2, SD2
4 – 2000 kW

An electronic motor braking device works on the principle of feeding direct current into the stator winding of three-phase induction motors. This generates a standing magnetic field which inhibits the movement of the squirrel-cage rotor. The braking effect depends on the size of the braking current. This is generated by rectifying the supply voltage. The use of thyristors with phase control allows the braking torque to be set over a wide range. DC braking causes a heating up of the motor.

In soft start and braking units or combi units, soft start and DC braking are represented in one unit. This enables very compact, universally applicable solutions.

Applications:
* Electronic braking 

Braking units 2,2 – 7,5 kW

Special versions, e.g. 480 V, please inquire

Braking units 15 – 200 kW

Up to 90 kW UL-certified for the USA and Canada.

Digital soft starter / Braking unit

Soft start, soft stop and braking of squirrel cage motors
2,2 – 90 kW

A voltage controller is similar in function to a soft starter. In difference to the soft starter, which always increases the motor voltage up to the nominal voltage, the voltage controller remains in the partially or fully modulated range, depending on the specified setpoint. This allows the user to adjust the motor torque over a wide range. It can also be used as a power controller for electric heaters.

Single-phase voltage controllers 1,5 – 18 A

Three-phase voltage controllers 6 A

A braking chopper or chopper is connected to a DC link. When a set brake voltage threshold is reached it switches an internal or external resistor (depending on the series) in a clocked mode. Thus the chopper effectively limits the voltage in e.g. a DC link. Typically, a braking chopper is used with a frequency inverter for demanding braking tasks (up to continuous braking) or to protect regenerative frequency inverters in the event of a mains failure.

Braking choppers with integrated braking resistors
2 – 55 kW

Braking choppers for external braking resistors
11 – 22 kW

Braking choppers for external braking resistors
22 – 1200 kW

A frequency inverter is the appropriate motor control device for continuous speed adjustment. In contrast to the soft starter, it does not operate the motor rigidly on the mains at a constant frequency, but regulates both the operating voltage and the operating frequency and can therefore run the motor energy-efficiently over a wide speed range. A regenerative frequency inverter also offers the possibility of recovering the braking energy, i.e. feeding it back into the supply.

Applications:
* Improvement in efficiency with reduced space requirements and costs 
* Energy efficiency and cost reduction

Frequency inverters
AC 110 – 480 V / 1,5 – 30 kW

Regenerative frequency inverter
3AC 200 – 480 V / 4 – 200 kW

Fully digital converters for DC drives

Analog DC converters for DC drives