7.2kV 800A High Voltage Vacuum Contactor with Corrosion Resistance for AC Motor Control
MKKG5-7.2 AC vacuum contactors are designed for power networks with AC frequency of 50Hz-60Hz, rated voltage of 7.2kV, and rated current up to 800A. These contactors provide remote making and breaking, frequent start, and control of AC motors in main loop applications.
Ideal for use in combination with fuse and protective devices as an alternative to vacuum circuit breakers.
Operating Environment Specifications
Environmental Conditions
- Ambient air temperature: -10℃ to +40℃
- Maximum installation altitude: 1000m
- Maximum mean monthly relative humidity: 90% (at minimum mean monthly temperature of 25℃)
- Operating conditions free from significant impact and vibration
- Environment without explosive gases or corrosive dust
- Protected from rain and snow exposure
Product Specifications
Model Configuration
Available in rated voltages of 7.2kV with rated currents up to 800A. Control voltage options include 110V, 120V, 220V, and 380V.
Design and Operation
Structural Components
The contactor consists of a base frame, electromagnetic mechanism, and vacuum interrupter. The electromagnetic mechanism operates the vacuum switch tube through armature, connecting lever, and draw bar components.
Operating Principle
When connected to control power supply, the magnet coil energizes and the armature drives the connecting lever to rotate, closing the moving and fixed contacts within the vacuum interrupter. The break spring compresses to store energy during this process.
After contact closure, the auxiliary switch connects the holding winding in series with the starting winding loop, throttling the coil to maintain the magnet in closed position. Disconnecting the control power supply releases the break spring, separating the main contacts and breaking the main circuit.
Vacuum Interrupter Construction
Composed of upper cover, lower cover, metal bellows, and ceramic tube. The enclosure utilizes corrugated porcelain tube made from 95 ceramic, offering extended creepage distance, high mechanical strength, heat resistance, and impact resistance.
Contact material is Cu-W-Wc alloy, providing excellent ablation resistance and low diversion closure values. This design reduces overvoltage caused by cut-off during interruption and extends electrical contact service life.
Electromagnetic System
Features DC double coil configuration with starting winding and holding winding, switched via auxiliary switch. Includes bridge rectifier for AC power supply operation. Offers optimal coordination between attractive force and spring force characteristics with low-noise, energy-efficient performance.
Optional Mechanical Padlock
Available with mechanical padlock feature. When closing coil is energized, the contactor closes and the mechanical padlock engages. Trip coil energization releases the padlock and contactor. In thermal state, reliable release occurs with trip coil voltage between 85%-110% of rated voltage.
Technical Parameters
Main Loop Configuration: 3-pole design
Control Power Supply: 110V, 120V, 220V, 380V at 50Hz/60Hz (custom options available)
Control Loop: DC electromagnet with AC control via power module
Rated Duty: Discontinuous long-time duty and repeated short-time duty (40% on-load factor)
Auxiliary Contact: Three normally open and two normally closed contacts, 5A heating current
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