C7-250A DC Contactor

Product Introduction

The BSB C7-250A DC contactor is designed for high-current DC switching applications such as electric vehicles, energy storage systems, and high-power charging infrastructures. With a continuous current rating of 250A and a breaking capacity of 2500A, it offers excellent performance under demanding load conditions. Its epoxy-sealed enclosure ensures safe operation in harsh or explosive environments, and flexible coil options (12/24V or 48/72V) enable easy integration across systems.

Product Features

• Heavy-Duty Switching: Rated for 250A continuous current, and capable of 2500A breaking at 320VDC.

• Low Contact Resistance: Just 0.2 mΩ at 250A, minimizing thermal rise and energy loss.

• Epoxy Resin Sealed: Fully sealed to prevent oxidation and contamination, IP67 rated.

• Wide Coil Compatibility: Supports 12/24VDC and 48/72VDC coil voltage configurations.

• Auxiliary Contact Options: Available with normally open (NO), normally closed (NC), or changeover (Z) auxiliary contacts.

• High Endurance Design: Withstands vibration up to 20G and extreme temperatures from -40°C to +85°C.

• Certified Safety: Compliant with UL, CE, TUV, and RoHS standards for global applications.

Typical Applications

• Main contactor in commercial EV battery systems

• Pre-charge and discharge relay for large BESS and UPS

• High-power DC charging equipment

• PV inverter switching and solar energy control

• Industrial or rail systems requiring vibration-proof HVDC contactors

Summary of Technical Parameters

Dimensional Drawing & Wiring Diagram

Vertical type with economizer

Horizontal type with economizer

FAQs About The BSBC7-250A DC Contactor

Q1: Does the C7-250A 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: Can the C7-250 operate in high-vibration applications like trucks or rail vehicles?
A2: Yes. It has been tested to withstand up to 20G vibration and is ideal for mobile, rail, or industrial use.

Q3: What is the conductor size requirement?
A3: The minimum cross-sectional area for external wiring is 75 mm².

Precautions for Use

To ensure safe, stable, and long-lasting operation of the C7-250A high voltage DC contactor, please follow the usage precautions below:

Mechanical Installation

• Always use spring washers to prevent screw loosening.

• Tighten mounting screws with a torque of 2.5–3.5 N·m as specified. Excessive torque may crack or damage the product.

• Do not use the contactor if it has been dropped or subjected to impact.

Wiring and Polarity

• The main contacts and control coil leads are non-polar, simplifying installation and preventing miswiring.

• Make sure the external terminal is in reliable contact with the main terminal.

• Do not allow grease, dust, or debris to accumulate on the terminals, as this may cause overheating.

Coil Surge Protection

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

• For models without an economizer, install a TVS or varistor (rated at 1.5–2× the coil voltage) across the coil terminals.

• ⚠️ Avoid using diodes for coil protection, as this may reduce the product’s breaking capacity.

Environmental Conditions

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

• The contactor is gas-sealed. High ambient temperatures or contact temperature rise will accelerate internal gas diffusion, shortening product life.

• Avoid placing the product near strong magnetic fields (e.g., transformers, magnets) or heat-generating components (e.g., fuses, shunts).
  ➤ If necessary, perform a temperature rise test to confirm safe distance and avoid overheating or burnout.

• Altitude limit: ≤4000m

• IP rating: IP67

Switching Performance and Lifespan

• This product is a high-voltage DC switch and has a defined electrical life.

• Once the contactor reaches end-of-life, it may lose the ability to disconnect properly.
  ➤ Do not exceed the rated switching capacity or total switching cycles.

• Design your circuit to cut power within 1 second in the event of contactor failure or sticking.

Load Characteristics

• For resistive loads, you may apply rated voltage and current directly.

• For inductive loads (L/R > 1 ms), a parallel inrush current protection device (e.g., TVS, varistor) must be installed.

Coil Drive and Switching Behavior

• If the coil and main contacts are operated continuously at rated voltage, then quickly reclosed after cutoff, coil temperature will rise, causing:

  • Higher coil resistance

  • Higher pick-up voltage than rated value
    In this case, consider:

  • Reducing the load current

  • Limiting continuous “on” time

  • Using a coil voltage higher than the rated pull-in voltage

• The coil drive power must exceed the coil’s rated power, otherwise the contactor’s cut-off performance may decline.

• For models with energy-saving circuits, the coil enters holding mode about 0.1s after energization.
  ➤ Do not interrupt power at that moment, as it may damage the contactor.

Others

• 🔙 Back to C7 Series DC Contactors

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