Review of Types of Pneumatic Key Accessories and Their Applications

In this article by Electrosheely, we aim to explore various types of accessories for pneumatic keys and analyze their unique applications. Join us for a detailed examination.

Pneumatic Keys:

Pneumatic keys are considered part of thermal-magnetic automatic devices and have a body that withstands continuous thermal and mechanical stress to handle nominal currents. These keys are available in two models: three-pole and four-pole, as well as fixed and withdrawable forms, customizable according to specific needs. They are used in electrical panels as main switches, master switches, or pneumatic automatic keys to meet various industrial requirements.

Types of Pneumatic Key Accessories:

To enhance the efficiency of these keys and remotely control them, a variety of accessories are utilized that improve the capabilities and functionalities of these devices. This article delves into reviewing these equipments and their operations, providing you with precise information about the added features to automatic keys.

Motorized Pneumatic Key

Motorized pneumatic keys typically utilize a make-and-break structure with charged springs. In this design, the spring of the key is charged either manually by a handle (manual charging mechanism) or by an electric motor, which engages the key and prepares it for operation.

By pressing the ON button on the key, the connection is established, and pressing the OFF button disconnects the key. Additionally, in case of an error, an electronic relay detects the fault current using sample transformers and issues a discharge command to the spring mechanism within a specified time. In other words, the current interruption mechanism is activated by the key in its active state.

Another method for charging a motorized pneumatic key is installing a pneumatic key motor on the key. This method allows remote charging of the key without the need for manual intervention. Although motorized pneumatic keys are more expensive than manually charged versions, they can also be manually charged if needed.

Shunt Relay and Overvoltage of Pneumatic Key

Motorized pneumatic keys employ bi-metal (overload protection) and magnetic coils (resistance to short-circuit current) to protect circuits. These keys serve as essential components in lighting and industrial electrical installations, safeguarding lines, machinery, and secondary power transformers to protect transformers.

Application of Pneumatic Keys in Input and Output Feeders

Pneumatic keys are installed on both horizontal and vertical busbars and serve to protect motors, capacitors, generators, busbars, and cables. A crucial point is that the micro-technology of pneumatic keys supports various electrical protections.

The control of pneumatic keys is managed through two types of relays known as shunt relays and undervoltage relays. These relays are installed inside pneumatic keys, and their delay feature is essential for maintaining synchronization. If there is a need to motorize pneumatic keys using an electric motor, it can be ordered together with the motor, along with two shunt relays, one of which could be an undervoltage relay.

Schneider Electric Undervoltage Relay for Pneumatic Keys

Motorized pneumatic keys are available with AC voltages of 110V and 220V, and the voltage type of the motor should be specified during purchase. In most cases, electric motorized pneumatic keys are chosen with 220V AC voltage.

Advantages of Automatic Pneumatic Keys

The advantages of automatic pneumatic keys are highly significant and effective. These advantages include:

– Immediate Operational Capability: Automatic pneumatic keys are ready for operation immediately after circuit disconnection in response to high currents or other factors.

– Short-Circuit Protection: The design of these keys ensures that if the key closes on a short-circuited circuit, the overcurrent relay quickly activates and disconnects the circuit.

– Key Status Control: By utilizing secondary contacts placed within the pneumatic key (four position contacts and one fault contact), the status of the key can be determined in various states such as open, closed, or fault occurrence, displayed in the control room.

– Network Protection: In some distribution networks, it’s necessary to automatically disconnect the circuit in case of reverse current or excessive voltage drop, and activate necessary alarms. Automatic pneumatic keys provide this capability.

– Emergency Use: During emergencies where automatic or manual entry of emergency generators or transformers is necessary for network continuity or periodic maintenance, only automatic keys can be used effectively.

Micrologic Protection Unit

The micrologic protection unit is recognized as a vital accessory for automatic pneumatic keys, offering various types of electrical protections. This unit addresses protections such as short-circuit, ground fault, neutral protection, and overload protection. By installing the micrologic protection unit on the key, an active control unit is enabled that not only displays nominal power, voltage, and current values but also measures them. This unit comes in various types with adjustable protection thresholds and delays through adjustable screws. These features transform the unit into a versatile and efficient tool in the field of electrical protection.

Short-Circuit Protection in Automatic Pneumatic Keys

Short-term (rms) and instantaneous protection are essential factors in selecting the type of I2T for delay in short-circuit protection.

Ground Fault Protection

Covering ground faults or residuals using type I2T for delay in protection.

Earth Leakage Protection

Operation without the need for external power supply, resistance to noise with Class A up to 10A.

Neutral Protection

In a three-pole automatic key, neutral protection is not possible. In four-pole automatic keys, neutral protection is achieved through a 3-position switch.

Unprotected (4P 3d) or Neutral Protection in Ir (4P 4d)

Overload Protection

Long-term rms and real thermal memory protection: Thermal image before and after relay operation, accuracy of settings limited by using different overload protection adjustment ranges through a Rating Plug. Overload protection can be deactivated using a special Rating Plug when in OFF mode. An overload LED warning indicator lights up yellow when the current exceeds the set overload threshold.

Advantages of Communication via COM Port

– Device Settings: The COM communication port can send device settings and update device performance settings.

– Relay Performance Causes: By using the COM port, relay performance causes can be sent to the system for identification of issues.

– Maximum Value Readings: Receive maximum values and ammeter measurements through communication with the COM port.

– Micrologic Power Circuit Protection: Micrologic protection units allow you to protect power circuits and send protection-related information.

Micrologic protection units for pneumatic keys are divided into four different categories: Micrologic A, Micrologic P, Micrologic E, and Micrologic H. These units indicate the level of key protection and include Micrologic 2, Micrologic 5, Micrologic 6, and Micrologic 7.

Auxiliary Equipment in Pneumatic Keys: Enhancing Performance and Safety

In the realm of pneumatic keys, auxiliary equipment such as trip relays, disconnect relays, undervoltage relays, auxiliary contacts, pneumatic key motors, and micrologic protection units play prominent roles. These components significantly contribute to improving the functionality and reliability of pneumatic keys, facilitated further by communications through COM ports.

Micrologic Protection Unit in Pneumatic Keys: Ensuring Security and Optimal Performance

The micrologic protection unit represents an intelligent electronic innovation in the realm of pneumatic keys, automatically safeguarding devices against short circuits, sudden current surges, and even delays in disconnection. This advanced unit, known as micrologic, utilizes state-of-the-art electronic technology to precisely measure and control essential parameters.

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Final Thoughts

This article has explored various types of pneumatic keys and their applications. It has also underscored the significance of auxiliary components in enhancing performance and circuit protection. Trip relays, disconnect relays, undervoltage relays, auxiliary contacts, pneumatic key motors, and micrologic protection units stand out as crucial auxiliary equipment for improving the performance and safety of pneumatic keys. These components not only enable remote control capabilities but also ensure protection against overcurrent, short circuits, and other electrical hazards. By utilizing these auxiliary devices, pneumatic keys are optimized for a wide array of applications, including industrial uses and electrical installations.

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