Comparison ColorWay CW-VR16-01D vs iKOS SVP-099D

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.

Time to turn off the device on the lower limit of voltage or current. This is a kind of "reaction time" of the relay: the period of time between reaching the lower limit and turning off the protected network segment.

The lower this value, the more advanced the protection will be, the lower the probability of failure of sensitive devices due to untimely operation of the relay. On the other hand, a high response rate for the lower limit is not as critical as for the upper one, and the shutdown time can be quite long — 1 s or more.

Also note that for some devices, this paragraph gives the minimum turn-off time (fastest response time), while in certain modes this time may be longer. For example, a voltage relay with a lower limit of 160 V may provide tripping after less than 0.05 s when the voltage drops below 120 V and tripping after 1 s when the voltage is in the range of 120 – 160 V, but above 120 V. This avoids unnecessary shutdowns with relatively weak and short-term voltage deviations. In the characteristics of such a device, 0.05 s will be indicated.

The device shutdown time on the upper limit of voltage or current. This is a kind of "reaction time" of the relay: the period of time between reaching the upper limit and turning off the protected network segment.

The lower this value, the more advanced the protection will be, the lower the probability of failure of sensitive devices due to untimely operation of the relay. Note that a short reaction time in this case is especially important, because too high a voltage or current is a serious danger to any device.

The lower voltage shutdown limit provided in the relay; when the voltage drops below this value, the device turns off the power to the protected network segment. Usually, this limit can be adjusted, and the specifications indicate the range of such adjustment.

Although the main danger for various electrical appliances is increased voltage, many devices do not tolerate too low voltage. Therefore, modern voltage relays provide shutdown not only on the upper, but also on the lower threshold.

The upper voltage shutdown limit provided in the relay is the voltage, when exceeded, the device turns off the power to the protected network segment. Usually, this limit can be adjusted, and the specifications indicate the range of such adjustment.

The method of managing the operating parameters provided in the device.

— Mechanical. Adjustment of parameters using mechanical switches, usually rotary, with scales printed next to them. In some models, these switches are manually adjusted, in others they must be turned with a screwdriver or other similar device. This method is simple, reliable and inexpensive, but not as convenient as digital adjustment, and has very low accuracy — for example, the re-closing time can be set with an accuracy of 20-30 seconds at best, and more often up to a minute or two.

— Digital. Adjustment of parameters using control electronic circuits. For such devices, it is mandatory to have a display: during adjustment, it displays a configurable parameter that can be changed by pressing the “+” (“Up”) and “—” (“Down”) buttons. Digital adjustment is somewhat more expensive than mechanical adjustment, but it significantly exceeds it in accuracy — the adjustment step can be 1 – 3 (seconds, volts, etc.).

The degree of protection of the housing according to the IP standard, which the device complies with.

This standard describes protection against the ingress of foreign objects and dust (first digit) and moisture (second digit) — for example, IP20. It is worth noting here that modern voltage relays are usually not designed for any moisture at all, so their water resistance is indicated at level 0. But in terms of the level of protection against foreign objects, the options can be as follows:

— 1 — protection against objects with a size of 50 mm or more; minimal, purely symbolic level of protection. — 2 — from objects 12.5 mm and thicker (in particular, fingers); — 3 — from objects 2.5 mm and thicker (from tools, thick wire); — 4 — from objects 1 mm and thicker (from wires, except for the thinnest ones).