Power limiter: features of connecting a single-phase and three-phase device, ohm-110 and ohm-310

Situations when, due to the lack of capacity of city power grids, it has to be limited at some facilities, are quite common. You can solve this problem using a power limiter. As soon as the set parameters are exceeded, the device disconnects the consumer from the network. Also, this device allows you to protect electrical wiring from unauthorized connections.

Functions and working principle

Power limiters can be used in three- and single-phase networks. Regardless of the model, the main task of these devices is to control the consumed active power and its limitation when the set values ​​are exceeded. However, modern devices are multifunctional and can be used to solve the following tasks:

• Protect against sudden voltage surges.
• In the event of a short circuit, they provide overcurrent protection.
• They can perform the functions of a relay in case of violation of the phase sequence or in case of imbalance of line voltages.

The device allows you to control the operation of the contactor and, in the event of a malfunction, is able to independently disconnect the circuit. Most often, according to the default settings, almost all of the protective functions of the arrester are disabled. Only the line voltage imbalance protection remains active. The rest of the functions are switched on manually.

The principle of operation of these devices is quite simple - they compare the indicators of the maximum allowable voltage and power coming from the local network.

As soon as a mismatch in the parameters is detected, the consumer is disconnected. In order for the flow of electricity to resume, it is necessary to reduce the load on the power grid. The reverse inclusion does not occur instantly, but with a small delay of several seconds.

Connection recommendations

Not only the organization supplying electricity is interested in using this device, but also the consumer. The installation of the limiter should be entrusted to a specialist. However, you can do it yourself, taking into account several factors:

• Load capacity under the contract.
• Response time at the moment of exceeding the set parameters and resuming the power supply.
• Power supply type.

Depending on the type of electrical network, you must purchase the appropriate device - three- or single-phase. The first factor will allow you to choose the right type of device, since in some situations a contactor may also be required.

There are some general requirementswhich must be observed when installing the limiter:

• The cross-section of the wires must be calculated according to the consumed load.
• The device must be designed for a specific indicator of current strength.
• Access to conductive parts of the device must be limited.
• All parameters must be set to the values ​​of the planned power consumption, and not the maximum.
• If the device is out of order, it is necessary to call a specialist.

Single phase device

ОМ-110 model is a single-phase power limiter. The features of connecting devices of this type can be seen on its example. First, the device must be installed in the seat. It can be mounted on a DIN rail. Connection to the mains is carried out in compliance with the phase and zero bus. The conductor from the load should be brought through a special hole to the transformer. It is this structural element that allows you to control the power of the consumed energy.

In the next step the contactor is connected in accordance with the diagram. Please note that this model can only work in conjunction with a contactor designed for switching voltage. The shutdown power is set using the potentiometer. Then the operating time of the limiter in case of overload and its return to normal state is set. When all the steps for connecting the device have been completed, you should check its operability.

For this, a supply voltage is applied and a load is connected, the power of which is inferior to the calculated one. If the green LED lights up, the device is activated. After that, the increased load is connected.

First, the overload LED should light up. After the set time has elapsed, the consumer will be disconnected.

Three-phase device

The three-phase power limiter ОМ-310 is designed to operate in a 380 V network, the power of which is in the range from 3 to 40 kW. The algorithm for connecting it is similar to a single-phase device. The only difference is the need to connect 3 phases and a neutral conductor. The front panel of the device is equipped with two indicators, with the help of which the OM-310 parameters are set and its operation is monitored.

The setting of this model is somewhat different from the OM-110. The main advantage of the ОМ-310 device can be considered the ability to connect to a PC for setting up. The load must be connected via current transformers. When installing the device, you will also need a contactor with which the voltage will be switched.