What Are Voltage Relays?

A voltage relay is an electronic control device. It has a control system (also known as an input circuit) and a controlled system (also known as an output circuit). It is usually used in automatic control circuits. A type of "automatic switch" for high current. Therefore, it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit. It is mainly used in the relay protection devices of generators, transformers and transmission lines as the starting element for overvoltage protection or low voltage blocking. ^[1]

Voltage relays are measuring relays with input and characteristic quantities as voltages. They are divided into overvoltage relays and undervoltage relays. The former acts as the voltage value increases to reach the set value, and then is in a post-movement state; the latter acts as the voltage value decreases to reach the set value, and then is in the released state. Voltage relays are of electromagnetic type and transistor type.

Formally, it can be divided into: electromagnetic voltage relay and static voltage relay (integrated circuit voltage relay).

From the structure type, it can be divided into: protruding fixed structure, protruding plug-in structure, embedded plug-in structure, guide rail structure and so on.

From the voltage action type, it can be divided into: overvoltage relay and low voltage (undervoltage) relay.

From the use mode, it can be divided into: auxiliary relay and non-auxiliary voltage relay. ^[3]

1. Structure and principle

The electromagnetic voltage relay is divided into a protruding fixed structure, a protruding plug-in structure, an embedded plug-in structure, and the like, and has a transparent plastic cover, which can observe the setting and specifications of the relay.

The electromagnetic voltage relay magnetic system has two coils, and the coil is connected to the base terminal. The user can connect in series and parallel as required, so that the setting range of the relay can be doubled.

The scale value and rated value of the electromagnetic voltage relay nameplate are the current when the coil is connected in series (in units of A) for the current relay and the voltage (in units of V) when the coils are connected in parallel for the voltage relay. Turn the pointer on the dial to change the reaction torque of the hairspring so that the action value of the relay can be changed.

Action of electromagnetic voltage relay: For an over-current (voltage) relay, when the current (voltage) rises to a setting value or greater than the setting value, the relay will act, the closing contact is closed, and the breaking contact is opened. When the current (voltage) decreases to 0.8 times the setting value, the relay returns, the movable contact is opened, and the movable contact is closed. For low-voltage relays, when the voltage decreases to the set voltage, the relay is activated, and the movable contact The point is opened and the break contact is closed.

2. Technical requirements

1. Relay rated voltage, setting range, power consumption, return factor.

2. Limit error of operating value: Under reference conditions, the limit error of each setting value of the relay does not exceed ± 6%.

3. Action value consistency: Under reference conditions, the consistency of the relay action value does not exceed 6% of the setting value.

4. Variation caused by temperature change: At the nominal limit temperature, the variation of the operating voltage does not exceed ± 5% of the setting value.

5. Action time: at 1.1 times the measured action value, the action time of the overvoltage relay is not greater than 0.12 s (for DY-32 34 / 60C not more than 0.15 s); at 2 times the measured action value, the action time is not greater than 0.04 s (not more than 0.06 s for DY-32 34 / 60C); when the low voltage relay is 0.5 times the actual measured operating value, the operating time is not greater than 0.15s.

6. Thermal performance: When the ambient temperature is 40 ° C, the relay can work under the long-term allowable voltage (see Table 1), without insulation and other component damage, and its coil temperature rise does not exceed 65 ° C.

7. Overload capacity: When the coils of the relay are connected in parallel, at the minimum setting value, when the voltage is uniformly increased from 1.05 times the setting voltage to 2.2 times the setting voltage, the relay moving contact should not have jitter that cannot work.

8. Insulation performance

a. Insulation resistance is not less than 300M.

b. Medium strength

1. Structure and principle

The static voltage relay is divided into a protruding fixed structure, a protruding plug-in structure, an embedded plug-in structure, a guide rail structure, etc., and has a transparent plastic cover (the guide rail type is fully enclosed). .

When the measured AC voltage is reduced by the isolation transformer, a voltage Ui proportional to the measured voltage is obtained, and then rectified after tuning. The rectified pulse voltage is filtered by a filter to obtain a DC voltage Uo proportional to Ui. In level detection, Uo is compared with the DC reference voltage Ue. If the DC voltage Uo is higher than the reference voltage, the level detector outputs a positive signal to drive the outlet relay, then this relay is in the operating state. Conversely, whether it is an over-voltage relay or a low-voltage relay, if the DC voltage Uo is lower than the reference voltage Ue, the level detector outputs a negative signal, and the relay is inactive.

2.Main technical parameters

1. Auxiliary power: AC / DC85-265V

2. Overload capacity: AC circuit allows 1.2 times rated value to be connected for a long time.

3.Voltage setting range:

With auxiliary source (0.1-99.9V, 40-450V)

No auxiliary source (19-130V, 85-265V, 180-440V)

4. Power consumption: The power consumption of the AC loop is less than 1VA (when the AC rating is 100V)

5.Setting error

a. Within the setting range, the absolute value of the setting average error is not greater than 3%, and the average error = (average of 5 measurements-setting value) / setting value × 100%.

b. Under the reference conditions, the maximum and minimum values of 5 times of action values measured on the same setting value should not be greater than 4%.

c. At the temperature of -10 ~ 50 , the absolute value of any set point error should not be greater than 4% of the set value.

d. Within the variation range of 80 ~ 110% of auxiliary voltage, the absolute value of any setting value setting error should not be greater than 4%.

6, action time

a. Over-voltage relay: 1.2 times of set value action time is not greater than 25ms; 2 times of set value action time is not greater than 20ms;

b. Low-voltage relay: The operating time of 0.5 times the setting value is not more than 20m.

7, return coefficient

a. The return coefficient of the overvoltage relay is 0.85 ~ 0.95;

b. The return coefficient of the low voltage relay is 1.02 ~ 1.12;

8. Return time: no more than 27ms.

3.Static active voltage relay

Static active voltage relays are used in generator protection, transformer protection and transmission line protection devices as starting elements for overvoltage protection or low voltage blocking. This relay is an integrated circuit static type relay with high accuracy, low power consumption, short action time, high return coefficient, intuitive and convenient setting, wide range, and use as a low voltage relay without jitter. There are auxiliary source voltage relays, the auxiliary power source uses switching power supply conversion, 85-265V AC and DC are universal, the working range is large, and it can work reliably from 1-450V.

4.Static passive voltage relay

Voltage relays are used in relay protection devices for generators, transformers and transmission lines as starting elements for overvoltage protection or low voltage blocking. This relay is an integrated circuit static type relay with high accuracy, low power consumption, short action time, high return coefficient, intuitive and convenient setting, wide range, and use as a low voltage relay without jitter. Passive voltage relays do not require a DC auxiliary power supply. They use a DIP switch to set the voltage value and use a digital override switch to switch. No calibration is required after the change. All can completely replace the electromagnetic voltage relay. Passive voltage relays adopt a protruding fixed structure, a protruding plug-in structure (JK-1, JK-1Q), and an embedded plug-in structure (A11K, A11H, A11Q) respectively. ^[1]