
MERZ, a German company successfully operating since 1946, is a global manufacturer of high-quality electromechanical main and compact switches. With its partners, it is present in more than 40 countries worldwide. KATKO is a Finnish electrical industry company, specializing in designing, manufacturing, and delivering leading solutions for the electrical installation sector. At KATKO, they are pioneers of high quality electrical switches and other installation products.
Main switches
The main switch is the cornerstone of every circuit. Its function is to disconnect the machine and all electrical connections from the mains during cleaning, maintenance and repair, as well as when the machines are idle for long periods. It must comply with IEC/EN 60947-3 for user category AC23.
The position of the main switch shall be clearly indicated, either by a visible separation of the contacts (open position) or by a clear indication of the position. The main switch shall also be capable of being locked in the “Off” position to allow safe servicing. The switch may also be used as an emergency switch but must then be properly marked with a red handle on a yellow background.
Main (service) or emergency stop switches are available in a variety of mounting options, allowing a wide range of applications with rated currents from 10A to 125A. Switches can be three or four pole or, on special order, multi-pole and equipped with auxiliary contacts if required.
KATKO switches in a stainless steel enclosure
A special version of switches for the most demanding users, featuring:
- Power range: 16-1600A and 16-160A (model with steel handle); IP66
- AISI 316L, acid-resistant (optional for model with polycarbonate handle)
- Designed for hygienic and other demanding environments
- Easy to install and to clean
- Rain protection with sloping top on RS models
- LKR1 stainless steel handle with optional lock or polycarbonate handle with three optional locks
- Tested according to IEC 60947-3
- Also available as EMC and EMC/EX protected
KATKO switches in heat-resistant aluminium housing
A special version of switches for the most demanding users, featuring:
- Power range: 16-200A
- Two protection classes F200 3H (FR) and F300 2H (FR3)
- FR meets the F200 standard for smoke and heat EN 12101-3, 200 °C for 3 hours
- FR3 meets the F300 standard for smoke and heat EN 12101-3, 300 °C for 2 hours
- IP66: Housing types A2, A4
- IP65: Housing types A5, A6
- Locking option
- Door locking with release mechanism
- High corrosion and UV resistance
- Excellent for severe weather conditions
- Tested in accordance with IEC 60947-3


Compact switches
Compact switches are available in a variety of mounting options, allowing a wide range of applications with rated currents from 16A to 630A. Switches can be three or four pole or, on special order, multi-pole and equipped with auxiliary contacts if required.
Selectable or toggle ridge switches
These switches are used for installation in control cabinets and distribution boards to control process variables in various buildings (residential and commercial buildings, hospitals, production halls, etc.).
They also allow direct control and operation of simpler machines or devices. Compact switches with different functionalities and rated current up to 10A are designed to enable the realization of applications for the control of various processes.
The ridge switches are available in different mounting options, allowing a wide range of applications with rated currents from 10A to 125A. The switches can be single or multi-pole and equipped with auxiliary contacts if required. They can also have a different number of positions depending on the requirements.

Switches with special functions
DC Switches
DC switches are specifically developed for disconnecting loads in DC circuits. They are specially designed for photovoltaic applications. The product range includes types that can withstand currents from 10A to 160A and can safely disconnect open-circuit generator voltages up to 1500 VDC.
Undervoltage (UVR) switches
MERZ UVR switches with undervoltage tripping are available for a power range from 32A to 63A. An undervoltage switch (UVR) is an electromechanical device that automatically disconnects when the supply voltage drops below a certain value. In this case, the switch lever moves back to the OFF position.

Program Manager Danfoss VLT/Vacon, Merz and Solcon
Gorazd Bernik, M.Sc.