High Voltage DC Relay Contactor 300A YV300

Key Design Features

• Sealed nitrogen contact chamber - the contacts work in a dry, inert atmosphere rather than open air, so oxidation and airborne dust stay off the contact faces and contact resistance holds steady over a long service life.
• Neodymium-iron-boron arc magnet - a DC arc will not fall away at a current zero crossing the way an AC arc does, so the magnet stretches it and drives it clear of the contact faces, cutting the material lost on every operation.
• Built-in energy-saving circuit board - the coil pulls pick-up current to close the contacts and then settles onto a lower holding current, so it runs cooler and your control supply is not carrying the closing current all shift.
• Built-in directional voltage control - direction handling sits on the board inside the unit instead of in the external control circuit, which keeps the drive side of the design simple.
• Compact body for the switching power - sealed construction allows a smaller unit than the duty would suggest, so this fits a crowded panel or battery box where a general industrial relay of similar rating would not.

Specifications

Switching Duty & Service Life

The steady rating is only half the story. Behind it sits a short-time ladder: the contacts are rated to carry 400 A for 120 minutes, 600 A for 20 minutes, 900 A for 30 seconds, 1200 A for 10 seconds and 1800 A for 0.6 seconds. That ladder is what a DC system actually asks for, because faults, inrush and pre-charge events push far more current through the bus than the running load ever does. Service life follows the same pattern. Mechanical endurance runs to 200,000 operations, while electrical endurance depends on what is being switched - 3000 operations at 300 A and 450 VDC, 1000 operations at 300 A and 750 VDC, and 500 operations at 160 A and 1000 VDC. Working near the top of the voltage range is entirely normal; plan a shorter service interval, or step up a frame in the same range if the duty never lets up.

Installation & Wiring

1. Land the main cables on the contact terminals. There is no polarity requirement, so either terminal can take the positive or the negative leg of the bus - which is what makes this straightforward in circuits where current flows both ways, such as a battery that charges and discharges through the same cables.
2. Keep the cable runs as short and symmetrical as the layout allows. Long, uneven busbar runs add inductance, and inductance is what makes a DC arc harder to interrupt.
3. Connect the coil to your control supply using the flying lead. If the standard lead-out will not reach the control terminals, ask for a different length when ordering rather than splicing inside the panel.
4. Tie the coil leads clear of the main current path so they cannot chafe against busbars or lie against warm cables.
5. Check the isolation between the coil circuit and the main contacts with a megohmmeter before first energising. That check is about your panel wiring, not the device.
6. Cycle the contactor a few times through the control circuit to confirm it picks up and drops out cleanly, then label the unit with the model and coil voltage.

Typical Applications

• EV and hybrid battery packs - used as the pre-charge device that brings the DC link up gently before the main contactor closes, or as the main switching point itself.
• DC charging equipment - connects and isolates the high-current DC feed on the output side of a charger, where an AC-rated device is not an option.
• Solar and battery energy storage - the main disconnect between a battery bank and its inverter, on a bus that stays live for most of the day and is only opened for isolation or service.
• Electric heating systems - a DC supply feeding heating elements, where the contactor carries the load for long steady periods rather than switching it rapidly.
• Industrial DC power cabinets - the position where a heavy DC circuit needs the switching reliability of an industrial relay in a sealed body, in a panel with no room for an open-frame contactor.

Environmental & Mechanical Ratings

Scale & Supply Capability

YongNeng is a relay manufacturer supplying signal relays, latching relays and high-power relays, together with a high-voltage DC contactor line that runs from 16A up to 400A. Because our range covers everything from light switching duty to heavy DC loads, buyers can consolidate several switching positions with one supplier instead of sourcing each rating separately. Power relays are offered in sealed and open construction, and contact wiring is arranged for straightforward installation. Tell us the current rating, switching duty and mounting space your project needs, and we will help you match the right relay or contactor to your build.

FAQ