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, it is possible to significantly extend the service life of low-power transformers. They also regulate power consumption between users. In addition, restrictors can be configured in such a way that unauthorized connections are not allowed. To date, 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. At a minimum, the limiters are capable of delivering power of 3 kW, and a maximum of as much as 30 kW. However, in this situation, much depends on the manufacturer. Additionally, such a parameter as delay is taken into account. It ultimately affects the ultimate voltage of the device. Overcurrent for single-phase arresters maximumcan be 3 A. It should also be borne in mind that sudden voltage surges are unacceptable for devices of this type.
What is the difference between three-phase arresters?
The power limiter (three-phase) keeps the voltage limit at 350 watts. In turn, its operating frequency is at around 70 Hz. At a minimum, the limiters are capable of holding a power of 5 kW, and a maximum of as much as 40 kW. Additionally, it should be borne in mind that they have a rather high rate of discreteness.
The shutdown delay, in turn, averages about 10 seconds. Three-phase modifications can withstand quite large power overloads. Voltage drops are also taken seriously. Of the shortcomings of these devices, it should be noted the great instability of the current in the relay contacts. Additionally, there are large measurement errors. Thus, three-phase limiters need more serious tuning.
How to connect the device?
The power limiter is usually connected above the input machine. In this case, the high-voltage wire must be near the starter. The zero bus is directly connected to the electricity meter. Connection to the transformer is carried out in series. For normal operation of the limiter, first of all, set the block.
The power connection is checked for each phase separately. The top pads should eventually all be in the top position. The electromagnetic latch is activated last. Pads of the second line must close all relay contacts. To avoidany 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 are checked, as well as the main power wire.
Limiter OM-630
This device is connected via a 35 mm rail. The OM-630 power limiter withstands the maximum voltage at the level of 300 V at an operating frequency of 60 Hz. The device is capable of delivering a minimum power of 4 kW, and a maximum of as much as 30 kW. The discreteness index of this model is good and is at the level of 0.2 kV. The restart delay is 5 seconds on average. With a sharp drop in voltage, the OM-630 power limiter is able to turn off quite quickly. The device can withstand a maximum current load of 5 A.
Device model OM-1
This model is connected through a special bus, which is located under the counter. The maximum switched current of the specified power limiter (the diagram is shown below) withstands 16 A. In this case, the device can be regulated from 3 to 30 kW. The degree of protection in OM-1 is IP20. The total reclosing delay fluctuates around 6 seconds. With an external AC transformer, the specified limiter is able to work. With a sudden voltage surge of 20 V, the device turns off automatically. Additionally, 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 for it, on whichthe body is fixed.
Connecting limiter OM-1-2
The power limiter OM-1-2 is connected through the introductory machine. In this case, the high-voltage wire must be located behind the cover of the device. 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 impulse to pass, a separate contact on the panel is activated. Blocks of the second line are used for external signaling of the limiter. Tubular entries of the device are checked as a last resort. To set the required mode, the last pair of pads is used.
Scheme for connecting a single-phase model with an electric latch
In this case, the first pair of shoes should be in a neutral position. Connection to the power supply is carried out through a special connector. On the first phase, the voltage is checked first. Relay contact K1 is used for the electromagnetic latch. Blocks of the second line in the limiter are intended for priority loading. To access an external alarm, contacts of different capacities are used. The third line pads are for mode setting only. Tubular entries are connected directly to the power cable.
Connection 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 has the ability to control the voltage limits. External signaling plays a key role in this case.
In order for the limiter to be able to withstand a large load, the first pair of shoes is placed in the neutral position. The starting impulse in the system is suppressed by an electromagnetic latch. Blocks of the second line are necessary only to overcome the priority load. In turn, the power is turned off due to the zero bus. The switch closes the circuit in the network, which is connected to the zero phase.
Open contact limiter connections
In order to connect a limiter with open contacts, it is important to set up the starter. After that, the first pair of pads is set to the top position. In this case, the introductory machine should be located immediately behind the power cable. Switches are used to avoid low-frequency overload. The current supply to the zero-sequence transformer occurs thanks to group automata, which are fixed on silicone seals.
Devices OM-630-2
The 630-2 power limiter can withstand the maximum voltage at 340 V at an operating frequency of 70 Hz. Its discreteness index is 3 kW. The device is connected to the meterthrough sealed contacts. The overload trip delay is approximately 40 seconds on average. The maximum voltage drop this limiter can withstand is 30 V. In turn, the system can handle an overload of 5 A. The measurement error for these models is quite small, and this should be taken into account. In addition, it is important to note that reactivation of the limiter is fast.
Connecting device OM-630-3
This power limiter is turned on (wiring diagram is shown below) via the bus. Group semiautomatic devices in this case are connected last. The top pair of pads must be in the up position before current is applied. In turn, the pair of the second line should be in a neutral position. Due to this, the voltage in the device quickly stabilizes. Special blocks are used to deal with priority overloads. They are attached directly to the electricity meter. You can always check the correct connection of the limiter, 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 the maximum as much as 33 kW. The discreteness of this limiter is quite significant and amounts to 0.3 kV. In turn, the turn-off delay is 6 seconds. Restarting the device is fast. Voltage drop maximumOM-310 is capable of withstanding 5 V. In turn, the current overload should not exceed 6 A. There are two switches in total in the device.
Devices for working with an external transformer
The 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 normally open.
It is additionally 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 must first be set to the upper position and then look at the display system. If the green LED is on, then the system is closed. Further, these pads are transferred to the 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, tubular inputs are brought to them sequentially. Next, it is important to close the electromagnetic latch. For this purpose, it is necessary to remove the protective cover and move the circuit wiring aside. The blocks of the third line are set to the upper position one by one. In this case, the user is obliged to monitor the display system. If the green LED lights up during the procedure, this indicates that the circuit is closing. Toexternal alarm is not activated in the system, it is necessary to disconnect the relay contacts. The tubular entries must then be reconnected.
