ISA-A

8–170 A and 200–600 V
ISA-A Analogue Soft Starter with motor protection and built-in bypass
Advantages at a glance
- Soft start and soft stop
- Current limit
- Build-in motor protection
- Build-in bypass
- Start/stop by dry contact
- Compact, small foot print
- Aluminum housing
- Integrated input voltage monitoring
Details
- ON – mains voltage connected
- Ramp up/down
- Run
- Overload
- Phase loss
- Over temperature
- Electronic overload
- Phase loss
- Starter over-temperature
- SCR protection by metal oxide varistors
- End of acceleration relay, N.O contact
- Fault relay, N.O contact
- Over temperature

- Pumps
- Compressors
- Fans
- Blowers
- Conveyors
- Starting from weak power supplies (diesel generators etc.)
Starter Type | kW at 400 V | Width (mm) | Height (mm) | Depth (mm) | Weight (kg) |
---|---|---|---|---|---|
ISA-A 8 | 4 | 120 | 232 | 105 | 2.6 |
ISA-A 17 | 7.5 | 120 | 232 | 105 | 2.6 |
ISA-A 31 | 15 | 120 | 232 | 105 | 2.6 |
ISA-A 44 | 22 | 120 | 232 | 105 | 2.6 |
ISA-A 58 | 30 | 129 | 275 | 185 | 5.0 |
ISA-A 72 | 37 | 129 | 275 | 185 | 5.0 |
ISA-A 85 | 45 | 129 | 380 | 185 | 8.4 |
ISA-A 105 | 55 | 129 | 380 | 185 | 8.4 |
ISA-A 145 | 75 | 172 | 380 | 195 | 11.8 |
ISA-A 170 | 90 | 172 | 380 | 195 | 11.8 |
Approvals

Current limit
The voltage increases linearly from the “Initial Voltage“ pre selected point. If the adjusted “Current Limit” is reached, the voltage will stop ramping and remain at its level until the current is reduced below the adjusted “Current Limit“ level. In that case ramp up time is prolonged until the current has reduced below “Current Limit” level

Although the current is limited the motor provides suitable torque to accelerate the driven load and reach “End of acceleration”. If the motor torque does not exceed the load torque the motor will not start. In the so rare cases severe damages might occur to the motor and starter.

Motor start measured with an oscilloscope
(Ch1, voltage; Ch2-4 current L1 – L3)
The oscillogram shows, the soft starter providing a smooth and stepless current and voltage ramp to the motor. The voltage ramps up until “Current Limit” is reached. After the motor is at nominal speed, the current will decrease, to the nominal motor current.
Bypass
Internal bypass
- This reliable components bypass the power electronics after the motor is at speed.
- In addition the starters provide an auxiliary contact, allowing signaling of a successful motor start.Attention! Many of our competitors call these auxiliary relays “a bypass contact”!
- The bypass function reduces the heat dissipation and eliminates the EMC load of the system.
Analogue
The analogue product line provides simple potentiometer settings for all the parameters:
- Familiar setting, similar to standard overload relays
- Easy commissioning
- Prior knowledge is not necessary
- Status display via LEDs
- ISA-A include motor protection functions