C7-300A DC Contactor

Product Introduction

The BSB C7-300A DC contactor is a high-capacity DC contactor designed for demanding high-voltage switching in electric vehicles (EVs), energy storage systems (BESS), and solar applications. Rated for 300A continuous current and 2500A max switching, the C7-300A offers superior endurance and minimal internal resistance. With a sealed epoxy resin body, optional auxiliary contacts, and support for 12/24V and 48/72V coils, it combines performance, flexibility, and safety in a single unit.

Product Features

• High Current & Voltage Support: Handles 300A continuously and up to 2500A at 320VDC.

• Proven Durability: Endurance tested across multiple voltage levels – 500V@300A (4,000 cycles), 750V@300A (2,000 cycles), and 1000V@200A (1,000 cycles).

• Low Contact Resistance: ≤0.2 mΩ at 300A ensures energy efficiency and thermal stability.

• Epoxy Sealed Enclosure: Prevents dust, oxidation, and moisture – rated IP67 for rugged environments.

• Advanced Coil Options: 12/24V and 48/72VDC supported with energy-saving economizer built-in.

• Auxiliary Contact Configurations: Supports NO, NC, and changeover types.

• Tested Shock & Vibration Resistance: Rated to 20G vibration and 50G impact for mobile use.

Typical Applications

• Power switching in large-scale electric commercial vehicles

• BESS systems with dynamic charge/discharge management

• Solar inverter arrays and photovoltaic control systems

• High-voltage fast charging stations

• Rail and marine HVDC electrical systems

Summary of Technical Parameters

Dimensional Drawing & Wiring Diagram

Vertical type with economizer

Horizontal type with economizer

FAQs About The BSBC7-300A DC Contactor

Q1: Does the C7-300A DC contactor have reverse surge protection?
A1: Only products equipped with a PWM economizer include a surge suppression circuit. If you choose a standard product without an economizer, you need to address the issue of counter-electromotive force (back EMF) from a design perspective.

Q2: What makes the C7-300A DC contactor ideal for 1000V systems?
A2: It has already undergone durability testing at 1000V, and its high insulation rating makes it suitable for long-term high-voltage applications.

Q3: Is a pre-charge circuit required for capacitive loads?
A3: Yes, pre-charge is strongly recommended to avoid contact sticking during first-time closure under high capacitance.

Precautions for Use

Please follow these safety and handling instructions to ensure optimal performance and reliability of the C7-300A high voltage DC contactor:

Mechanical Installation

• Use spring washers during installation to prevent screw loosening.

• Recommended tightening torque for mounting screws: 2.5–3.5 N·m. Do not exceed this limit to avoid casing damage.

• Do not use the product if it has been dropped or mechanically impacted, even if no visible damage is observed.

Wiring and Polarity

• Both the main contact terminals and coil leads are non-polarized, simplifying installation.

• Ensure the external wire terminal is in firm and clean contact with the product’s terminal.

• Avoid any contamination from grease, dust, or debris, as this can lead to overheating at the terminals.

Surge Protection for Coil

• For products with economizer, a built-in reverse surge absorption circuit is provided—no external protector needed.

• For models without economizer, install a TVS diode or varistor rated at 1.5–2× the coil voltage in parallel with the coil terminals.
  ⚠️ Do not use a diode, as it may reduce the contactor’s breaking capacity.

Environmental and Layout Conditions

• Operating ambient temperature: –40°C to +85°C

• The sealed chamber inside the contactor contains gas; excessive ambient temperature or heat from load current will accelerate gas diffusion and shorten lifespan.

• Avoid installation near strong magnetic fields (e.g., transformers, magnets) or heat-generating components (e.g., fuses, shunt resistors).
  ➤ If installation near such components is unavoidable, conduct a temperature rise test to confirm safe distance.

Switching Behavior and Electrical Life

• This product is a high-voltage DC switch and has a defined electrical life. Once it reaches end-of-life, it may lose its disconnection ability.

• ➤ Always design the system to cut off power within 1 second in case the contactor fails or sticks.

• Do not use the contactor beyond its rated current or life parameters.

Load Requirements

• For resistive loads, rated current/voltage may be applied directly.

• For inductive loads (L/R > 1 ms), install a parallel inrush current protection device such as a TVS diode or varistor.

• For capacitive loads, a pre-charge circuit is mandatory. Without it, the large inrush current at contact closure may cause contact welding.

Coil Drive Requirements

• If the contactor is repeatedly operated at full rated voltage and immediately reclosed after cut-off, the coil’s internal temperature will rise, increasing resistance and raising pull-in voltage.
  ➤ In this case, consider:

  • Reducing load current

  • Limiting continuous ON time

  • Using a coil voltage slightly higher than rated pickup voltage

• The coil driver circuit must provide sufficient power (> rated coil power). Undervoltage may reduce the contactor’s breaking performance.

Energy-Saving Circuit Note

• For models with energy-saving circuits, the coil will automatically transition to holding mode approximately 0.1s after power-on.
  ⚠️ Do not attempt to switch off at that moment, or it may damage the internal coil driver.

Others

• 🔙 Back to C7 Series DC Contactors

• 📄 Download the C7-300A Specification PDF

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