Product Description
The RQ900-7.5KW is a bypass-type soft starter for three-phase induction motors, available in 220V/380V/400V/420V/440V/480V/660V/690V configurations (15A at 380V/400V/420V). Built on power electronics and microprocessor control with SCR-based phase control, it limits inrush current to 2-4x rated current during startup, then switches to a bypass contactor for efficient, low-heat continuous running, requiring no cooling fan. An external bypass contactor is required for installation.
Key Features
- 3 start modes: Current-limit / Voltage-ramp / Kick-start ramp
- 2 stop modes: Free stop / Soft stop (prevents water hammer)
- Bypass operation after startup, no cooling fan required, lower heat and energy loss during continuous run
- Real-time 3-phase current display with independent calibration
- Bilingual LCD (Chinese/English), stores last 12 fault records
- Dual programmable relay outputs + dedicated bypass relay output + 4-20mA analog output + RS485 Modbus RTU (standard)
- Requires external bypass contactor (sized to match motor rated current)
Applications
- Pumps & Fans, soft-stop mode prevents water hammer, bypass operation reduces running heat for continuous duty
- Conveyors, gentle load engagement, less mechanical shock on belts and gearboxes
- Compressors, controlled acceleration protects valves and reduces pressure spikes
- Crushers & Mixers, handles high starting torque loads with kick-start ramp mode
Technical Parameters
| Parameter |
Specification |
| Model |
RQ900-7.5KW |
| Rated Power |
7.5kW (10HP) |
| Applicable Motor |
Squirrel-cage induction motor |
| Start Modes |
Current-limit (50–600% adj.) / Voltage-ramp / Kick-start ramp |
| Stop Modes |
Free stop / Soft stop |
| Bypass Contactor |
External, required (not included) |
| Cooling |
Natural air cooling (no fan, bypass-type) |
| Protection Rating |
IP20 |
| Communication |
RS485 Modbus RTU (standard) |
| Analog Output |
4–20mA |
| Protections |
Phase loss, overload, overcurrent, over/under-voltage, 3-phase imbalance, underload, start timeout |
| Ambient Temp / Altitude |
-25°C~+40°C / ≤2000m |
| Starting Frequency |
≤15 starts/hour |
Voltage / Current Options
| Voltage |
Rated Current |
| 220V/240V |
30A |
| 380V/400V/420V |
15A |
| 440V/460V |
15A |
| 480V/500V |
13A |
| 660V |
11A |
| 690V |
11A |
Selection Tip
Recommended soft starter power = Motor Power × Load Factor (Pump/Fan: 1.2, Conveyor: 1.3, Compressor: 1.5, Crusher/Mixer: 1.6). Not sure which factor applies? Use our Soft Starter Selection Calculator: https://www.softstarterpro.com/blogs/selection-tools/soft-starter-selection-guide
