What is a Modular Contactor? Working Principle, Advantages

If you’re looking for a switching device to control small capacity loads without any hum during operation, a modular contactor may be the solution you need. These compact devices can be mounted onto din rails, making them ideal for use in small electrical enclosures and cabinets. Unlike power contactors, they offer silent operation, making them perfect for indoor applications such as hotels and residential buildings. In this article, we’ll take a closer look at what modular contactors are, their advantages, selection parameters and common applications.

What is a Modular Contactor?

The modular contactor is a type of switching device that is used to control the small capacity loads without making any hum during its operation. It can be mounted onto din rail. It is compact in size and can be used in small electrical enclosures and cabinets.

These devices are designed to be installed on DIN Rail bars in combination with the low voltage portfolio offer. They provide safe switching and control of different applications plus protection against over-voltages and current peaks. They can also provide cost effecting solution, thanks to the low power consumption of DC coils.

The operation of the modular contactor is identical to a power contactor.

1-The coil of the contactor is energized.

2- Main contacts change position. (From NO to NC or NC to NO)

3- Electrical energy is transmitted from the supply side to the load

A power contactor generates a hum during the switching. You can hear this disturbing sound even if the cabinet door is closed. A modular contactor ensures silent operation. Therefore it is also referred to as a silent contactor. This is the most important feature that distinguishes the modular contactor from the power contactor.

The modular contactor is preferred in indoor applications due to its silent operation. It meets the needs of applications such as hotels and residential buildings. Generally, it is used to control the lighting loads. It is also used in the switching of small fans, pumps, elevators, and heaters.

They play an important role in realizing widespread applications, such as load-shedding circuits, and access control with card readers in apartments and hotels. Thanks to them, a complete shutdown of the whole power supply or of the individual circuit when leaving
the facilities can be realized.

Modular Contactor Advantages

It has the following benefits for the users.

It has a hum-free operation and low power consumption.
It dissipates less heat.
It is easy to install.
The modular contactor is similar to contactor relays (auxiliary contactors) in terms of contact combination. 1NO + 2NC, 2NO + 2NC etc.

modular contactor contacts — *Contacts of modular contactors*

It is compact and does not take up much space. It has a low price.
Accessory mounting options are very limited compared to power contactors.
It looks like miniature circuit breakers. Because it has a din-rail profile. It may be difficult to distinguish visually when used with MCBs inside the enclosure. But the general appearance of the panel looks very fine with the usage of mod. contactors.
It is generally produced up to 15 kW. Therefore it can be used for the switching of low loads.
The coils of the advanced models can be supplied with AC and DC. Besides they have surge protective functions.
Some models can be controlled manually.
It is equipped with contact indications.

Manual control and contact indication — *Manual control and contact indicators*

Modular Contactor Selection Parameters

When selecting a modular contactor, the below parameters should be considered:

Combination of contacts.
Rated operational voltage.
Rated operational current.
Control (or coil) voltage.
Ambient air temperature.
Electrical and mechanical durability.

If you use a modular contactor in lighting applications, you should control the type and quantity of lighting fixtures that will be connected to one contact of the contactor. Especially in today’s world where the use of LED lighting is increasing, the contactor must be able to withstand the nominal and inrush currents of the lighting fixtures.