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11.01.21 en / 335A

•  According to IEC/EN 60947-4-2

•  2-phase motor control

•  For motors up to 11 kW at 3 AC 400 V

•  Separate settings for start and brake time, as well as  

  starting and braking torque

•  No braking contactor necessary

•  Function test of brake circuit before softstart

•  With automatic standstill detection

•  Current monitoring

 

- to protect the power semiconductors

 

- for device protection at stalled motor

•  Maintenance- and wearfree

•  Auxiliary  DC 24 V

•  Monitors undervoltage and phase sequence

•  With input to detect motor temperature via PTC (variant /_1_)

•  3 relay outputs for indicaiton of status and fault with LED-indication

•  Width: 112.5 mm

0277233

•  Motor with gear, belt or chain drive
•  Fans, pumps, conveyor systems, compressors
•  Woodworking machines, centrifuges
•  Packing machines, door-drives

The devices slowly ramps up the current on two phases, therefore allowing 
the motor torque to build up slowly. This reduces the mechanical stress on 
the machine and prevents damage to conveyed material.

Start/Stop switch

When the motor is on full speed after the starting with start/stop switch 
S the semiconductors are bridged with internal relay contacts to prevent 
internal power losses and heat built up. When stopping the motor via start/
stop switch S braking is started. 
The braking current flows until the motor standstill is detected but not longer  
(max. 20 s) through the motor windings.

Monitoring relay 1 (contact 13-14)

The relay energizes at the end of the softstart ramp and de-energizes at the 
beginning of the braking cycle. (operation with bridged semiconductors).  
When a failure occurs the relay de-energizes when the semiconductors 
switch off.

Monitoring relay 2 (contact 13-24)

This relay energises as soon as the unit is ready for operation after connecting 
it to power. If any error occurs the monitoring relay 2 will be de-energized 
immediately. The power output will be switched off.

Monitoring relay 4 (contact 43-44)

This relay is energized when motor standstill is detected. It will be reset 
by starting the motor

The monitoring relay 4 is de-energized if an error 

occurs.

Input P1/P2/P3 to monitor the motor temperature 

(variant /_1_)

To monitor overtemperature onnb the motor a bimetallic contact can 
be connected to P2 / P3. When overtemperature is detected the power 
semiconductors switch off and all relays de-energize.
On P1/P2 up to 6 PTC sensors can be connected. On detection of 
overtemperature, short circuit or broken wire (in sensor circuit) the power 
semiconductors switch off and all relays de-energise.
The fault is reset by disconnecting the power supply temporarily after the 
temperature on the motor is down again.

Power Electronics

MINISTART
Softstarter with braking function
BL 9028

Approvals and Marking

Applications

Function

Softstarters are electronic devices designed to enable 1-phase or 3-phase 
induction motors to start smoothly. By means of internal current monitoring 
we realise different protective functions, when stalling the motor or during 
heavy duty starting. The semiconductors are bridged after softstart by relay 
contacts. This reduces power dissipation and heating. The device parameters 
are adjusted using potentiometers. LEDs indicate the status of the device.

Product Description

Function diagram

M10208_b

t0 : start
t4 : stillstand detection
t0-t1 : brake function test
t1-t2 : ramp up time
t3-t4 : braking time

t

t1

t1

t0

t2

t3

t4

t0

L1/L2/L3

T1

43-44

13-14

A1/A2

X1(+)
/ X2

M Mot

n

13-24

T2/T3

Translation

of the original instructions

All technical data in this list relate to the state at the moment of edition. We reserve the right
for technical improvements and changes at any time.

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