22KV Medium Voltage Circuit Breaker Isolation Mechanism

The Ring Main Unit (RMU) is a critical component in modern medium-voltage power distribution networks, ensuring uninterrupted and safe power supply. At the heart of the RMU is the operating mechanism, which controls switching devices, particularly for the incoming feeder—the main point where electricity enters the unit.

Cotenele’s 22KV Medium Voltage Circuit Breaker Isolation Mechanism is engineered for high precision, durability, and safety. It supports both manual and electrical operation modes, features advanced interlocks to prevent unsafe operation, and integrates seamlessly with Gas-insulated Switchgear (GIS), Environment-friendly Switchgear, and Air-insulated Switchgear used across industrial, railway, municipal, and renewable energy projects.

Model

What is a Circuit Breaker Mechanism?

The 22KV Medium Voltage Circuit Breaker Isolation Mechanism is the heart of the RMU’s switching capacity. It is a pre-stored energy device designed to perform the heavy duty of making and breaking electrical current under both normal load conditions and fault conditions. The mechanism described utilizes a distinct dual-spring system for its operation:

Closing Mechanism: The closing action is powered by a tension spring. During the charging process, this spring will be stretched. Once the command is received, the spring will be released beyond its center point, rapidly contracting to push the moving contact point into close contact. This' super center 'action ensures fast and stable closing speed, unaffected by the operator's operating speed.

Opening Mechanism: Conversely, the opening (or tripping) action is powered by a compression spring. When the circuit breaker is closed, it simultaneously compresses and releases the spring, storing the energy needed to cut off the circuit later. when the trip signal is sent, the spring will be released, causing the contacts to separate at high speed, thereby safely extinguishing the arc.

This design inherently supports reclosing functions—a crucial feature for transient fault management—and boasts a remarkable mechanical life, often exceeding 10, 000 operations, which underscores its reliability..

What is an Isolation Mechanism?

While the circuit breaker interrupts current, the isolation mechanism (or disconnector) provides a visible and verifiable gap in the circuit for safety during maintenance. In the RMU switchgear, the isolation mechanism works with the circuit breaker mechanism together. These two operation mechanism are mechanically interlocked to prevent unsafe sequences of operations. Generally, the interlock system ensures the isolator cannot be opened under load or that the circuit breaker cannot be closed unless the isolator is in the correct position. When combined, this assembly guarantees operational safety, physically separating the circuit from the source to protect personnel working downstream.

What are the features of our products?

A notable feature of this operating mechanism is its split-button design. In many industrial environments, dust and accidental operation are primary concerns. To mitigate this, the control interface is separated:

The actual mechanical pushbuttons are located on the mechanism housing itself.

The expansion operation button is installed on the external panel of the RMU casing and is equipped with a dust-proof and misoperation proof cover.For this situation, The operators can interact with the device from the outside without exposing sensitive internal components to pollutants, while the protective cover prevents accidental contact and triggers device operation.

Operation Instructions

The 22KV Medium Voltage Circuit Breaker Isolation Mechanism support manual and electrical operation, so they are flexible for installation, testing, and normal service.

A. Charging (Energy Storage)

Manual Charging: Insert the specific operating handle into the charging socket located at the lower right part of the mechanism. When the operator rotate the handle clockwise until heard an audible "click" . This indicates that the closing spring is fully charged, and the mechanical indicator confirms the stored energy status.

Electrical Charging: When the auxiliary power is supplied to the unit, the internal motor automatically activates. It drives the mechanism to charge the spring. Once charging is complete, a microswitch cuts off the motor supply, holding the energy ready for a closing command. It is critical to verify the secondary wiring is correct before relying on electrical operation.

B. Closing Operation

Manual Closing: The operator press the green button, This action will instantaneously releases the charged closing spring, driving the circuit breaker to close the main circuit.

Electrical Closing: when the closing solenoid coil is solenoid. The solenoid plunger will moves, mechanically releasing the spring latch. when the stored energy is released, then close the circuit breaker. After closing, the mechanism will automatically re-compresses the opening spring (storing energy for the next trip) and activates the interlocks to prevent a second closing command while the breaker is already closed.

C. Opening Operation

Manual Opening: Press the red button. This releases the previously compressed opening spring, causing the breaker to trip and interrupt the current flow.

Electrical Opening: Energize the shunt trip (opening) coil. The magnetic force releases the opening spring latch, allowing the spring to expand and force the contacts apart instantly.

Appearance and dimensions

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