LS MC-18b AC Contactor for Elevator Applications

The LS MC-18b AC contactor, designed specifically for elevator use, belongs to the Metasol series and features excellent performance and easy installation.

Basic Parameters

Rated Operating Current: 18A

Rated Operating Voltage: Up to 690VAC

Pole Count: 3 poles

Coil Voltage: Available in multiple specifications including 24VDC

Applicable Motor Capacity: Capable of controlling 7.5kW motors at 380VAC

Structure and Installation

Mounting Method: Supports DIN rail mounting or screw mounting for easy fixation in control cabinets

Terminal Type: Equipped with screw terminals for simple and reliable wiring

Dimensions: AC version measures approximately 45mm × 73.5mm × 87.4mm; DC version measures approximately 45mm × 73.5mm × 103.6mm

Performance Characteristics

Protection Rating: IP20, preventing accidental contact with live parts by fingers

Contact Configuration: 3 normally open (NO) main contacts plus 1 normally open (NO) and 1 normally closed (NC) auxiliary contact, meeting various control requirements

Service Life: Electrical service life up to 2.5 million operations under load conditions; mechanical service life up to 15 million operations

Application Scenarios

Suitable for circuits with rated voltage up to 660VAC, 50Hz or 60Hz, and rated current ranging from 9A to 85A. It can be used for frequent starting and control of AC motors. In elevator control systems, it is applied to control the start, stop, forward and reverse rotation of elevator motors.

Detailed Working Principle of LS MC-18b AC Contactor for Elevator Applications

The LS MC-18b, a dedicated AC contactor for elevators of the Metasol series, operates based on the principle of electromagnetic induction and mechanical linkage. Its core function is to automatically connect and disconnect circuits using electromagnetic force, with special optimizations for elevator application scenarios.

1. Core Structural Components

1. Basic Working Process (Core Principle)
2. Power-off State (Released State)

No current flows through the coil (terminals A1/A2), so the stationary iron core has no magnetism.

The movable iron core remains in the open position under the action of the reaction spring and its own gravity.

Main contacts (L1-T1/L2-T2/L3-T3) are disconnected, cutting off the main circuit; auxiliary contacts maintain their initial state (NO contacts open, NC contacts closed).

2. Power-on Pull-in Process

The control circuit applies the rated voltage (e.g., 24VDC, 220VAC, etc.) to the coil, which generates an alternating magnetic field.

The stationary iron core is magnetized, producing electromagnetic attraction that overcomes the tension of the reaction spring to pull in the movable iron core.

The movable iron core drives the contact bracket to act synchronously through the transmission mechanism:

Main contacts close, connecting the main circuit loads such as elevator motors.

Auxiliary NO contacts close while NC contacts open, realizing control signal switching and status feedback.

The shading ring on the core’s pull-in surface eliminates vibration and noise caused by alternating magnetic fields, ensuring stable pull-in.

3. Power-off Release Process

When the coil loses power or the voltage drops below the release value, the electromagnetic attraction disappears.

The movable iron core resets under the action of the release spring, driving the contacts to return to their initial state.

Main contacts disconnect, cutting off the main circuit; auxiliary contacts reset (NO contacts open, NC contacts closed).

III. Special Functions and Principles in Elevator Applications

1. Adaptation to Frequent Operation

With an electrical service life of up to 2.5 million operations and a mechanical service life of up to 15 million operations, it meets the frequent start-stop requirements of elevators.

Main contacts are made of silver alloy material, resistant to high-temperature ablation, ensuring reliable on/off performance.

2. Safety Protection Mechanism

Undervoltage Release Function: Automatically releases when the control voltage is too low, preventing elevator out-of-control incidents.

Contact Arc Extinguishing Design: Adopts a closed arc extinguishing chamber to quickly extinguish electric arcs, improving safety and service life.

3. Control Logic Coordination

Links with the elevator control system to realize motor start/stop/forward-reverse rotation (car lifting/lowering) control.

Auxiliary contacts provide contactor status feedback, which is used for elevator operation status monitoring and fault diagnosis.

1. Key Technical Points and Precautions
2. Coil Voltage Matching: Select a coil specification consistent with the control voltage of the elevator control cabinet (e.g., MC-18b-24V, MC-18b-220V, etc.).
3. Load Type Adaptation: With a rated current of 18A, the MC-18b is suitable for 7.5kW motors at 380VAC, matching loads such as elevator door motors and control cabinet fans.
4. Installation and Wiring:

Supports DIN rail or screw mounting; ensure secure fixation to reduce the impact of vibration.

Main circuit and control circuit terminals are separately arranged to avoid interference.

4. Maintenance Points: Regularly inspect contact wear, coil temperature rise, and spring elasticity to ensure safe elevator operation.
5. Working Principle Summary

Essentially, the LS MC-18b AC contactor for elevator applications is an electromagnetically controlled automatic switch. Through the core mechanism of “pull-in when energized, release when de-energized”, it realizes remote and frequent on/off control of the elevator main circuit. Its special design endows it with high reliability, long service life, and safety protection features in elevator applications, making it an indispensable key component in elevator electrical control systems.