Comparison DigiTOP VP-3F63A vs DigiTOP V-protector VP-16AS

The number of phases for which the relay is designed.

— 1. Single-phase power is known to everyone from classic 230 V household sockets. Actually, some relays for this voltage are even made in the form of socket adapters (see "Installation"). However, models are also produced for other values of alternating voltages — for example, 110 V.

— 3. Three-phase 400 V power supply is used mainly for high consumption devices for which 230 V networks do not provide enough power. Also note that switchboards in private houses are often connected to a three-phase electrical network, with further power distribution for individual phases. However, in such cases, it is more reasonable to use three separate relays for each of the phases, and not one three-phase device: in the first case, only part of the home network will lose power in the event of a power failure, in the second, the entire network.

— 1/3. A specific variant used exclusively in the phase selection relay. Such models take three phases as input, and only one is fed to the load; see "Device" for details.

Regular way to install the relay.

— Into an outlet. Devices plugged into a standard 230 V socket. Usually they look like adapters that are inserted directly into the socket, while the case of such a device has its own socket for a standard plug. Such models are extremely easy to use — just insert the plug into the outlet; as a result, they are mobile and can be easily moved from place to place as needed. On the other hand, "socket" relays can only be used to protect individual devices, and their functionality is noticeably more modest than that of rail-mounted ones.

— On a DIN rail. Installation on a standard rail used for mounting various devices in switchboards. Such relays are designed to protect fairly large segments of the network — for example, an entire apartment; they are more functional and designed for high currents than "socket", however, the installation of such a device requires professional skills.

Width expressed in unit units. This unit is used to measure the width of rack-mounted devices and makes it easy to estimate how much space you need. Width in unit is always expressed as whole numbers, 1 unit is approximately equal to 17.5 mm. There are models 1U, 2U, 3U and more

The rated power of the relay in kilovolt-amperes, in other words, the maximum apparent load power with which the device can normally operate.

From a physical point of view, kilovolt-amperes and kilowatts mean the same thing, but in kW it is customary to indicate only the active power of the load (see below), and in kVA — full. In AC networks, these powers can vary because active power (the power consumed by resistive-type devices such as heaters) is added to reactive power (the power consumed by capacitors and inductors). The apparent power is calculated from these two quantities.

When selecting control relays for AC networks, it is best to take into account the full power, especially if you plan to connect equipment with electric motors to the device. However, for many modern household appliances, only active power is given in the characteristics — in kilowatts. There are calculation methods that allow converting active power into total power, depending on the type and characteristics of the load; such techniques can be found in special sources.

Rated switching current for which the control relay is set. In some models, this parameter can be changed at the request of the user; for such devices, the current value set in the factory settings is indicated (usually, this is the maximum indicator).

For a voltage relay (see “Device”), the rated current is the maximum current allowed for the device and the network segment protected by it for an unlimited time, in fact, the maximum current in normal operation. Exceeding this current is allowed, but not for long (up to several minutes) and not much, not higher than the maximum current (see below). And devices with the functions of a current relay or a power relay can work as follows: if the actual current is between the rated and maximum, the relay goes into the “delayed off” mode, and turns off the power after a certain period of time (for example, 10 minutes). This avoids both overload from long-term operation at high currents, and unnecessary power outages at large, but short-term permissible loads.

Maximum switching current allowed for the control relay. This is the maximum current that the device can safely pass through itself. And for models with current relay functions (see "Device"), this is also the default threshold of instantaneous operation — the current at which the relay instantly turns off the power to the load. In many models, you can set a lower threshold, but not a higher one.

Measurement accuracy provided by the device. In this case, different types of measurements may be implied, depending on the purpose of the relay (see "Device"). Note that in power relays and multifunctional devices, the measurement accuracy for voltage and current is usually the same, and a common parameter is given in the characteristics for them.

Accuracy is indicated by the maximum measurement error provided by the device. First of all, the operation accuracy depends on this parameter: the lower the error, the smaller the actual deviations from the specified operation parameters. For modern control relays, an indicator of 3 – 5% is considered acceptable, 1.5 – 3% is not bad, 1 – 1.5% is good, less than 1% is excellent. However, in fact, it is also worth choosing according to this parameter, taking into account how sensitive the connected load is to the accuracy of the specified operation parameters.

Also note that many modern relays are equipped with digital displays that can display various parameters. In such models, the measurement accuracy also determines the accuracy of the readings of such a built-in "tester".

— Display. As a rule, control relays are equipped with simple segment LCD displays that can display numbers and some special characters. This screen performs two main functions. Firstly, during operation it displays key network parameters - voltage, power and/or power, as well as notifications of problems; Some models provide several separate displays, each with its own parameter. Secondly, the screen is used when changing device settings.

— Operation indicator. A pointer indicating the operation of a device, and often a specific mode of operation. Note that in this case we are talking about the simplest indicators - for example, in the form of an LED, which lights up green in normal mode and lights up red after the protection is triggered. The display is not considered an operation indicator, although it can perform such a function.

— Thermal protection. A safety system that turns off the device when it reaches a critical temperature. Some models also provide a shutdown when the permissible heating rate is exceeded. This function serves as additional insurance in case of malfunctions in the relay itself (for example, if the settings are lost and the device does not respond to overload), and in case of fire (in case of fire, the equipment must be de-energized).

— Memory of emergency operations. The function...of saving data on the state of the network during emergencies. Allows you to assess the situation of what happened after resuming work.