A power limiter is a device that regulates the supply of electricity to a home. It works, as a rule, in a network with alternating current. Thanks to modern limiters, the service life of low-power transformers can be significantly extended. Also, with their help, energy consumption between users is regulated. Additionally, limiters can be configured so that unauthorized connections are unavailable. Today, all devices of this type are divided into single-phase and three-phase models.
Features of single-phase limiters
A single-phase power limiter has a voltage limit of 300 V. The operating frequency of the device is on average 60 Hz. Minimum limiters are capable of delivering a power of 3 kW, and a maximum of as much as 30 kW. However, in this situation, much depends on the manufacturer. Additionally, a parameter such as delay is taken into account. It ultimately affects the voltage limit of the device. The current overload for single-phase limiters can be a maximum of 3 A. It should also be borne in mind that sudden surges are unacceptable for devices of this type.
What is the difference between three-phase limiters?
The power limiter (three-phase) limit voltage holds at 350 watts. In turn, its operating frequency is at around 70 Hz. Minimum limiters are capable of holding power of 5 kW, and a maximum of as much as 40 kW. Additionally, it should be borne in mind that they have a fairly high discreteness indicator.
The shutdown delay, in turn, is on average about 10 seconds. Power overloads of three-phase modifications can withstand quite large ones. Voltage drops are also perceived as serious. Among the disadvantages of these devices, it should be noted the large instability of the current in the relay contacts. Additionally, there are large measurement errors. Thus, three-phase limiters need to be configured more seriously.
How to connect the device?
The power limiter is usually connected above the input circuit breaker. In this case, the high-voltage wire should be near the starter. Directly the zero bus is connected to the electricity meter. Connection to the transformer is carried out in series. For normal operation of the limiter, the block is first set.
The power connection is checked for each phase separately. The upper pads should ultimately all be in the upper position. The electromagnetic latch is then activated last. The pads of the second line should close all relay contacts. To avoid any overload, the device is equipped with a special alarm. The last pair of pads is necessary to set the desired mode. After fixing the limiter, the tubular entries as well as the main supply wire are checked.
OM-630 limiter
This device is connected via a 35 mm rail. The maximum voltage limiter OM-630 can withstand 300 V at an operating frequency of 60 Hz. The device is capable of producing at least 4 kW of power, and a maximum of as much as 30 kW. The discreteness index for this model is good and is at the level of 0.2 kV. The re-enable delay is on average 5 seconds. With a sharp voltage drop, the OM-630 power limiter is able to turn off quite quickly. The device can withstand a maximum current load of 5 A.
The device model OM-1
This model is connected via a special bus, which is located under the counter. The maximum switching current indicated by the power limiter (circuit shown below) can withstand 16 A. In this case, the device can be adjusted from 3 to 30 kW. The degree of protection in OM-1 is IP20. The total delay of re-inclusion varies around 6 seconds. With an external AC transformer, the specified limiter is capable of working. With a sharp voltage jump of 20 V, the device turns off automatically. In addition, it should be noted that this limiter is quite simple to install. This is due to the fact that a special rail is included in the kit, to which the body is fixed.
Connection of OM-1-2 limiter
The OM-1-2 power limiter is connected via an input circuit breaker. The high-voltage wire should be located behind the device cover. First of all, it is important to connect all the contacts to the electricity meter. Next, you need to configure the zero bus in the shield. Lastly, the starter is activated, which is located above the zero sequence transformer.
The first three blocks of the limiter are connected directly to the relay. In order for the pulse to pass, a separate contact on the panel is activated. Pads of the second line are used for external signaling of the limiter. The tubular entries of the device are checked last. To set the required mode, an extreme pair of pads is used.
Connection diagram for a single-phase model with an electric latch
In this case, the first pair of pads should be in a neutral position. Connection to the power supply is via a special connector. In the first phase, the voltage is checked first. For electromagnetic latch, contact K1 is used. The pads of the second line in the limiter are designed for priority load. To access the external alarm use contacts of different capacities. Pads of the third line are intended solely for setting the mode. The tubular entries are directly connected to the power cable.
Wiring diagram with closed contacts
Connecting a limiter with closed contacts involves the use of discrete switches. The display system is checked by special LEDs. Thus, the user is able to control the voltage limits. External alarm in this case plays a key role.
In order for the limiter to be able to withstand a large load, the first pair of blocks is placed in a neutral position. The start pulse in the system is suppressed by the electromagnetic latch. Pads of the second line are necessary exclusively to overcome the priority load. In turn, power outage occurs due to the zero bus. A switch that connects to the zero phase closes the chain in the network.
Open Contact Limiter Connections
In order to connect a limiter with open contacts, it is important to configure the starter. After that, the first pair of pads is set to the upper position. The introductory machine should be located immediately behind the power cable. To avoid low-frequency overload, use switches. The current is supplied to the zero sequence transformer thanks to group machines, which are mounted on silicone seals.
Devices OM-630-2
The maximum voltage limiter 630-2 is able to withstand at 340 V at an operating frequency of 70 Hz. The discreteness index is 3 kW. The device is connected to the meter through closed contacts. The shutdown delay during overload is on average about 40 seconds. The maximum voltage drop this limiter can withstand is 30 V. In turn, the system can handle overload of 5 A. The measurement error for these models is quite small, and this should be taken into account. It is additionally important to note that the re-activation of the limiter is quick.
Connecting the OM-630-3 device
This power limiter (connection diagram shown below) is activated via the bus. Group semiautomatic devices in this case are connected last. The upper pair of blocks before applying current must be in the upper position. In turn, the pair of the second line should be in a neutral position. Due to this, the voltage in the device quickly stabilizes. To combat priority overloads, special blocks are used. They are attached directly to the electricity meter. The correct connection of the limiter can always be checked based on the indicators of the display system.
Single-phase model OM-310
To connect this model to the network, a 35 mm rail is used. The power limiter 310 is designed for a voltage of 250 V at an operating frequency of 45 Hz. The minimum power can be set to 5 kW, and a maximum of as much as 33 kW. The discreteness of this limiter is quite substantial and amounts to 0.3 kV. In turn, the shutdown delay is 6 seconds. Re-enabling the device is quick. The voltage drop maximum OM-310 is able to withstand 5 V. In turn, the current overload should not exceed 6 A. There are two total switches in the device.
Devices for working with an external transformer
A power limiter of this type is connected, as a rule, using a 40 mm rail. The introductory machine in this case should be under the box next to the power cable. The device is connected to the electricity meter last. The zero bus is connected to the first two contacts, which are short-circuiting.
It is also important to install a starter that regulates the operation of the zero sequence transformer. Before this, the user must configure the first pair of pads on the device. To do this, they should first be put in the upper position and then look at the display system. If the green LED lights up, then the system is closed. Further, these pads are placed in a neutral position so that the signal passes unhindered. Then the relay contacts are configured.
First of all, they should be thoroughly cleaned. In this case, the tubular entries are connected to them sequentially. Next, it is important to close the electromagnetic latch. To this end, remove the protective cover to the side and move the circuit wiring. Pads of the third line are set to the upper position alternately. In this case, the user must monitor the display system. If the green LED lights up during the procedure, this indicates that the circuit is closing. To prevent external alarms in the system, disconnect the relay contacts. After this, the tubular entries must be reconnected.