In-Line Soft Starter丨BK-ZHR9 Series 220V/380V (15KW-400KW) 

Product Overview

The ZHR9 Series Online Soft Starter (Online Intelligent Motor Soft Starter) is an advanced digital soft starting solution, tailored for medium-to-high power three-phase AC asynchronous motors. As a professional Non-Bypass Soft Starter, it supports three start modes (voltage ramp start, current-limiting start, torque start) and two stop modes (free stop, timed soft stop), realizing smooth start to reduce grid impact and motor wear.

This intelligent motor soft starter is equipped with 10+ core protection functions, including input phase loss, output phase loss, overload, overcurrent, overvoltage, undervoltage, underload, overheating, phase sequence error, and thyristor breakdown protection. It supports RS485 communication (Modbus-RTU protocol) and Chinese/English dual-language display, adapting to 220V/380V voltage levels and star/internal delta connection methods. With IP20 protection level and forced air cooling, this industrial soft starter ensures long-term stable operation in harsh industrial environments (-10℃~40℃).

Its core design focuses on high reliability, precise control, and strong expandability. Through optimized circuit layout and heat dissipation structure, this in-line soft starter meets the continuous operation demands of critical equipment such as large pumps, fans, and conveyors in medium-to-high power scenarios requiring a reliable soft starter.

Applications

The ZHR9 Series Online Industrial Soft Starter is widely applied in medium-to-large industrial scenarios, heavy-load operations, and key infrastructure, providing stable soft start solutions for equipment with high starting torque and power requirements as a professional motor soft starter:

Heavy Industry & Metallurgical Auxiliaries

• Medium-sized non-ferrous metal processing equipment powered by Online Soft Starter
• Ore crushers, ball mills, and mineral processing machinery equipped with motor soft starter
• Metallurgical hoisting tools, ladle transfer equipment matched with in-line soft starter
• Steel processing auxiliary drives supported by soft starter

Mining & Construction Materials

• Mine belt conveyors with dedicated conveyor soft starter (a type of Non-Bypass Soft Starter)
• Cement mill drives, rotary kiln auxiliary equipment powered by Online Soft Starter
• Stone crushers, sand making machines equipped with motor soft starter
• Construction tower crane auxiliary drives supported by soft starter

Water Treatment & Environmental Protection

• Large sewage lifting pumps with specialized pump soft starter (matched with Online Soft Starter)
• Industrial aeration blowers equipped with fan soft starter (a type of motor soft starter)
• Chemical dosing pumps powered by pump soft starter (supported by in-line soft starter)
• Desalination plant high-pressure pump drives with soft starter

Chemical & Petroleum Industry

• Chemical reactor agitator drives equipped with Online Soft Starter
• Oil drilling rig auxiliary pumps powered by motor soft starter
• Large air compressors, reciprocating pumps with pump soft starter (a type of Non-Bypass Soft Starter)
• Pipeline transportation pump drives supported by soft starter

Power & New Energy Auxiliaries

• Small power plant boiler feed pump drives with Online Soft Starter
• Solar energy storage system auxiliary motors equipped with motor soft starter
• New energy vehicle production line heavy-duty conveyors with conveyor soft starter (powered by in-line soft starter)
• Wind turbine auxiliary drive equipment supported by soft starter

Agriculture & Food Processing

• Large agricultural machinery (combine harvesters, tractors) equipped with Online Soft Starter
• Grain drying equipment drives powered by motor soft starter
• Large feed grinder, mixer drives matched with Non-Bypass Soft Starter
• Food processing line auxiliary machinery supported by soft starter

Product Features

Triple Start Modes, Adapt to Diverse Loads (Online Soft Starter)

This Online Soft Starter supports voltage ramp start (smooth start for general loads), current-limiting start (grid protection for high-impact loads), and torque start (high-torque start for heavy loads). It flexibly matches different equipment characteristics, making it an ideal motor soft starter for diverse scenarios.

Comprehensive Protection System, Safe & Reliable (Non-Bypass Soft Starter)

This Non-Bypass Soft Starter integrates 10+ core protections including input/output phase loss, overload, overcurrent, overvoltage, undervoltage, underload, overheating, and phase sequence error. Dual overload protection (inverter + motor) avoids equipment failure under heavy loads, extending motor service life for this soft starter.

Intelligent Communication & Centralized Control (Soft Starter)

Equipped with RS485 communication interface and Modbus-RTU protocol, this motor soft starter supports remote start/stop, parameter adjustment, and fault monitoring. It facilitates centralized management of multiple devices, reducing on-site operation costs for Online Soft Starter users.

Dual-Language Display & Intuitive Operation (Motor Soft Starter)

This Online Soft Starter supports Chinese/English bilingual operation interface, with detachable operation panel and clear LED status indicators. Parameter setting is simple, and fault codes are displayed intuitively for quick troubleshooting of this soft starter.

Pump-Specific Custom Functions, Scenario Optimization (Soft Starter)

This motor soft starter supports 4 pump-matching functions (float switch, electric contact pressure gauge, water supply/drainage liquid level relay), optimizing start-stop logic for water supply/drainage systems. It realizes automatic operation of pump equipment, making it a professional pump soft starter under the Non-Bypass Soft Starter category.

Flexible Installation & Strong Expandability (In-line Soft Starter)

This in-line soft starter supports wall-mounted installation and cabinet-type installation (soft starter cabinet), adapting to different on-site space requirements. Optional programming relays and 4-20mA analog output meet personalized expansion needs for Online Soft Starter applications.

Stable Heat Dissipation & Environmental Adaptability (Industrial Soft Starter)

This industrial soft starter features forced air cooling design and sealed heat dissipation structure, effectively isolating dust and moisture. IP20 protection level and -10℃~40℃ operating temperature range ensure stable operation in harsh industrial environments, making it a reliable motor soft starter.

Specifications 

Model Comparison Chart

Note: The size and weight vary depending on the power range, and are subject to the customized industrial motor soft starter product.

Installation Dimensions

Soft Starter Installation Dimensions

External Keyboard Installation Dimensions

FAQ For BK-ZHR9 Series In-Line Soft Starter (15–400kW)

Q1: What is an in-line soft starter, and how does it differ from a bypass soft starter?
A: An in-line soft starter (like the BK-ZHR9 series) controls motor voltage through thyristors during both startup AND normal operation, without switching to a mechanical bypass contactor. In contrast, a bypass soft starter transfers the load to a contactor after startup to reduce heat and energy loss. The in-line design is simpler, more compact, and ideal for applications with short run times, infrequent starts, or where minimal components are preferred.

Q2: Why would I choose an in-line soft starter over one with built-in bypass?
A: Choose an in-line soft starter when:

• Your application runs intermittently (e.g., crushers, presses, mixers)
• You prioritize lower upfront cost and simpler wiring
• Cabinet space is limited
• Continuous full-load operation is not required
  The BK-ZHR9 eliminates the need for internal contactors, reducing failure points and maintenance—making it highly reliable for duty cycles under 30 minutes of continuous run time.

Q3: Does the BK-ZHR9 generate more heat than bypass-type soft starters?
A: Yes, because current always flows through the thyristors during operation. However, the BK-ZHR9 is engineered with enhanced thermal management, robust heat sinks, and intelligent overload protection to handle this efficiently within its rated duty cycle. For applications with long continuous runs (>30 mins), a bypass-type starter may be more suitable—but for most industrial intermittent loads, the BK-ZHR9 performs reliably and cost-effectively.

Q4: Can the BK-ZHR9 be used for frequent start-stop operations?
A: Yes, but with consideration of the duty cycle and cooling time. The BK-ZHR9 supports multiple starts per hour (depending on motor kW and ambient temperature). For example, a 55kW unit can typically handle 6–10 starts/hour with adequate cooldown. Always consult the thermal capacity curve in the manual to ensure safe operation under your specific cycle.

Q5: What protection features does the BK-ZHR9 in-line soft starter include?
A: The BK-ZHR9 offers comprehensive motor and device protection, including:

• Overload (electronic thermal relay)
• Phase loss / phase imbalance
• Overcurrent / short-circuit (requires upstream fuse or breaker)
• Overvoltage / undervoltage
• Thyristor fault detection
• Stall and jam protection
  All protections remain active throughout operation—even during ramp-up and steady state.

Q6: Is the BK-ZHR9 suitable for high-power applications up to 400kW?
A: Absolutely. The BK-ZHR9 series scales up to 400kW (630A) and is commonly used in heavy-duty applications like rock crushers, large conveyors, agitators, and hydraulic pumps. Its solid-state in-line design ensures consistent torque control and smooth acceleration, even under high inertia loads.

Q7: Do I need external components when installing the BK-ZHR9?
A: Yes—unlike integrated bypass models, the BK-ZHR9 requires an upstream circuit breaker or fuse for short-circuit protection, as thyristors cannot interrupt fault currents. A line contactor is optional but recommended for remote isolation. No external bypass contactor is needed (since it’s in-line by design), simplifying the control logic while maintaining safety compliance.