What is PKS in electrical engineering: a complete guide to package switches

In the world of electrical installation and industrial automation, abbreviations can baffle even an experienced technician if he rarely encounters a particular segment of equipment. One such term is PKS, which is often found in old schematics, machine documentation and control panels. Understanding what lies behind these three letters is essential to properly maintaining, repairing or upgrading electrical circuits.

In simple terms, then Packet Switch Switch (although it is more correct to talk about a switch) is a manual control device that allows you to open or close electrical circuits under load. Unlike a simple switch, the PKS design allows you to switch currents of a certain strength without the formation of a dangerous arc that could damage the equipment. It is the reliability and compactness that made these devices the standard for many decades.

In this article we will analyze in detail the device, operating principle and scope of application of these devices. You will learn how they differ from modern analogues, how to choose them correctly and why you can still find them in existing electrical installations. Let’s figure out whether it’s worth replacing them with circuit breakers or whether their functionality remains relevant.

Abbreviation and purpose

First, it’s worth understanding the terminology, since confusion often arises in the professional environment. Abbreviation PKS literally stands for Packet Switch Switch (or simply Batch Switch). The key word here is “batch”, which indicates the specifics of the design: the device is assembled from several separate sections strung on a common shaft. Each such section, or “package,” is responsible for switching one phase or group of contacts.

The main purpose of this device is to manually switch alternating or direct current circuits with voltages up to 660 V and a frequency of 50-60 Hz. Batch switches are widely used to control asynchronous electric motors, in switchboards, on control panels for cranes, machine tools and other industrial equipment. They allow you not only to turn the power on and off, but also to reverse the direction of rotation of the motor or switch winding connection patterns.

⚠️ Attention: Despite the presence of an arc extinguishing mechanism, PKS are not intended for frequent switching under full load. Their mechanical and electrical wear resistance is limited, so for systems that require constant switching, it is better to use contactors.

It is important to note that in modern documentation and on the labeling of new devices the term PKS may be less common, giving way to more common names like "batch switch" or "switch". However, the design essence remains the same: it is a multi-position manual control device with a fixed handle position.

Design features and device

The package switch device is an engineered system that ensures safety and reliability. The basis of the design is a set of insulating washers made of durable plastic or textolite. Inside these washers there are moving and fixed contacts. The moving contacts are mounted on a rotary shaft, which is driven by a control handle.

A key element of safety is having fluoroplastic washers and spring mechanism. When the handle is turned sharply, the spring instantly compresses and releases, providing rapid opening or closing of the contacts. This is critical to minimizing arcing time. Fluoroplastic inserts located next to the contacts, when heated by an arc, release a gas that extinguishes it, preventing a short circuit between phases.

The device body is usually made of durable plastic that is resistant to mechanical shock and temperature changes. Depending on the degree of protection (IP), the housing can be open (protected only from accidental contact) or closed (protected from dust and splashes). The switch shaft is sealed to prevent moisture from entering the contact group.

Internal structure of the contact group

Inside each package there is a fixed contact fixed in an insulating washer and a moving contact on the rotating mechanism. When the shaft is rotated, the movable contact slides over the fixed one, ensuring a reliable connection. The design allows you to easily increase the number of poles by simply adding new packages to the shaft.

A variety of designs allows you to choose models for specific tasks:

• 🔹 Open type: Designed for installation in closed cabinets where dust and moisture are prevented.
• 🔹 Protected type: It has a casing that prevents foreign objects from entering from the outside.
• 🔹 Sealed type: Equipped with seals, which allows their use in conditions of high humidity or dust.

Operating principle and technical characteristics

The operating principle of the PKS is based on the mechanical opening and closing of electrical contacts. The operator turns the handle, which transmits force through the shaft to the moving contacts. Thanks to the spring mechanism, switching occurs quickly and clickily, which guarantees the stability of the connection and the absence of “bouncing” contacts. This is especially important when operating inductive loads such as electric motors.

Specifications package switches are strictly regulated by standards. The main parameters are rated current, operating voltage and number of poles. Rated current is the maximum current that the device can carry in continuous operation without overheating. Exceeding this value leads to melting of the contacts and failure of the device.

Below is a table with the main technical parameters of common series of package switches:

Parameter	PV Series (Low Power)	Series P (Industrial)	Series G (Sealed)
Rated current	up to 10 A	up to 63 A	up to 25 A
Voltage(AC)	up to 380 V	up to 660 V	up to 500 V
Number of poles	1-2	1-4	2-3
Degree of protection	IP20	IP30-IP40	IP54-IP65

An important aspect is the switching capacity. PKS is capable of withstanding short-term overloads, but is not designed to protect against short circuits. To do this, fuses or circuit breakers must be installed in the circuit.

Areas of application of package switches

Despite the advent of more advanced electronic controls, package switches remain in demand in many industries. Their simplicity and reliability make them ideal for use as input devices, operating mode switches and emergency switches.

In the domestic sector and small businesses, PKS can often be found as the main switches in distribution boards of garages, small workshops or country houses. They allow you to completely de-energize an object with one movement of the hand, which is convenient when carrying out repair work or in case of fire danger.

In industrial automation these devices are used for:

• ⚙️ Switching the connection diagrams of electric motor windings (for example, from “star” to “delta”).
• 🔄 Reversing the direction of rotation of the shafts of machine tools and mechanisms.
• 🔌 Switching control and alarm circuits in operator consoles.

PCS occupy a special niche in systems where visual position indication is important. The switch handle clearly indicates whether the circuit is on or off, unlike some circuit breakers whose lever position does not always clearly indicate the state of the contacts inside.

Advantages and disadvantages compared to analogues

To objectively assess the place of PSCs in modern electrical engineering, it is necessary to compare them with alternatives, such as circuit breakers and contactors. Packet switches have a number of undeniable advantages that allow them to maintain their position in the market.

The main advantage is compactness. A package switch takes up significantly less space in the panel than an equivalent current switch with fuses. In addition, they are highly resistant to vibration and mechanical stress, making them ideal for moving machinery and transport.

However, there are also disadvantages:

• ❌ Limited resource: The mechanical part wears out faster than modern automatic machines.
• ❌ Lack of protection: The PKS will not turn off the circuit in the event of a short circuit or overload on its own.
• ❌ Difficulty of modernization: Unlike modular DIN rail systems, replacing PCS often requires custom selection and drilling of holes.

⚠️ Attention: When replacing an old PKS with a modern circuit breaker, make sure that the new device has sufficient breaking capacity. A simple one-to-one replacement without taking into account the characteristics can lead to an accident due to a short circuit.

However, for simple switching tasks where automatic protection is not required, PKS remains a cost-effective and reliable solution. Their cost is typically lower than complex control systems, and their design allows for easy visual condition monitoring.

Installation, maintenance and safety rules

Correct installation package switch - the key to his long service. The device should be installed vertically so that contact wear products and gases formed during arc extinguishing can freely exit through the provided openings. The fastening must be rigid, without distortions, so that the shaft rotates freely, without jamming.

The wires are connected via screw terminals. It is important to use wires with a cross-section corresponding to the rated current of the switch, and to crimp the terminals carefully. Poor contact will result in heating, melting of the insulation and possible fire. After installation, it is necessary to switch the device several times to ensure smooth operation and clear fixation.

Check sequence after installation:
1. Visual inspection of screw tightening.
2. Checking the insulation resistance with a megohmmeter (at least 10 MOhm).
3. Mechanical testing (5-10 shifts without load).
4. Apply voltage and check operation under load.

PCS maintenance is minimal, but necessary. Periodically you should clean the case from dust and check the condition of the contacts. If soot appears on them, it is carefully removed with a small file or glass paper without damaging the surface of the silver. It is strictly forbidden to lubricate moving parts with ordinary oil - it attracts dust and can ignite.

Frequently asked questions (FAQ)

Can PKS be used for short circuit protection?

No, package switch is not a circuit breaker. It is intended for switching purposes only. To protect against short circuits and overloads, fuses or circuit breakers must be included in the circuit.

What is the maximum current that modern PKS can withstand?

Industrial series of batch switches such as PV or PKP, can switch currents up to 63 Amperes (sometimes up to 100 A in special versions). For high currents, switches or withdrawable circuit breakers are used.

Why does the packet switch buzz during operation?

The hum may occur due to vibration of the contacts when current passes, loosening of the mounting screws, or dirt getting inside the mechanism. It is necessary to check the tightness of the contacts and clean the device if necessary.

What is the difference between a PKS and a cam switch?

Structurally, they are similar, but cam switches have a more complex cam system, allowing the implementation of complex switching circuits (many positions and closure combinations), while PKS usually has a simpler circuit (on/off or reverse).