DE3118416A1 - Circuit arrangement for controlling an electromechanical relay which is supplied from an AC mains power supply - Google Patents

Abstract

The aim of the invention is essentially to develop a circuit for controlling an electromechanical relay which is supplied from an AC mains power supply, which circuit enables a direct drive from control electronics having an extremely low intrinsic electrical power consumption. However, in this case, a maximum of only four connecting terminals are intended to be available for connection of the supply voltage, the load and the triggering element for the switching command. In order to solve this problem, the invention proposes a circuit in accordance with Figure 4. This circuit is characterised in that a capacitor (C) is connected in parallel with the relay (RE) in order to hold the relay during the negative half-cycle of the AC voltage when driving the relay using a thyristor (TH) which switches through only in the positive half-cycle. <IMAGE>

Description

Circuit arrangement for controlling one from an alternating

Mains powered electromechanical relay The invention relates to a circuit arrangement according to the preamble of claim 1.

To switch high loads with small control voltages or control currents relays are often used. For controlling the relay excitation winding However, considerably higher currents are required than to operate the control electronics are required in today's semiconductor technology.

The invention is therefore based on the object of a circuit arrangement of the type described at the outset, which have a direct control made possible by control electronics with extremely low power consumption. Here however, there should only be a maximum of four terminals for connecting the supply voltage, the load and the tripping element are available for the switching command, such as e.g. for brightness control devices in the house installation due to existing ones Installation is required because retrofitting additional lines is hardly possible is.

This task is achieved by the characterizing features of the claim 1 solved. Further developments of the invention are the subject of the subclaims.

Based on the drawings, more details and advantages of the Invention explained. It shows: FIG. 1 a simple circuit arrangement of a Electronic installation switch, where an electromagnetic switch is used to switch the load Relay is used, Figure 2 shows a possible circuit arrangement, where a triac is used to turn the electromagnetic relay on and off is, Figure 3 shows a further embodiment of a circuit arrangement for implementation of the method according to the invention, in which a thyristor is used, Figure 4 the circuit arrangement according to the invention, in which to switch the electromechanical on and off Relay a thyristor is used as a switch.

In Figure 1 is the basic circuit diagram of an electronic installation switch shown, in which an electromechanical relay RE is used to switch the load L. will. The two outer connections 1 and 2 are connected to the load L, e.g. glow or Fluorescent lights connected. Connections 3 and 4 are made via the actuator T 1 and / or further actuating auxiliary units T 2 to TN connected. Simultaneously 1 serves as a connection point for the neutral conductor N and connection 4 for the phase line L 1, which can also be connected to any actuation extension TN could. This inevitably results in the phase line L 1 at the same time Reference line for each actuation point T 1 to TN is.

To control the relay RE, which is expedient from the anyway to The available mains voltage can now be excited is a suitable switching element necessary. Since the excitation voltage is an alternating voltage (mains voltage) acts, a triac TC could be used to switch the relay RE on and off according to FIG which would be controlled by the upstream control electronics = SE. Triacs, however, already have a considerably higher power requirement for control as is required for the operation of the control electronics SE. In contrast are thyristors TH better suited, however, no alternating voltage, only direct voltage can switch.

According to FIG. 3, for example, a control of the relay RE would be directly from the control electronics SE possible without this being uneconomical Supply voltage circuits would have to be created. The thyristor TH is a Bridge rectifier GL connected upstream, because of its high gate sensitivity can be controlled directly by the upstream electronics. At this Circuit arrangement, however, a further connection 5 is required because the phase line L 1 at connection 4 is no longer simultaneously used as a reference line for the auxiliary actuation units TN can be used. According to the task, however, there will be a maximum of four Connections required.

The circuit arrangement according to the invention according to FIG. 4 with the saving a fifth connection must therefore be seen as a major advantage. A thyristor TH is also used to switch the relay RE on and off, although the excitation voltage is derived directly from the AC mains voltage. As soon as the thyristor TH is activated, it switches during the positive half-wave by. During the negative half-cycle, the thyristor remains in the blocking state. In order to but during the non-excited negative half-wave (at 50 Hz - 10 ms) the armature of the relay RE does not drop out, the relay excitation winding becomes a capacitor C. connected in parallel.

If dimensioned sufficiently, it charges itself during the positive Half-wave, i.e. while the thyristor TH switches through, on a enough high voltage during the negative half-wave for another Sufficient excitation so that the armature of the relay RE does not drop. The diode D 1 ensures that the thyristor TH is reversed during the negative half-cycle is not charged. The resistor R is used to control the excitation current during the to reduce positive half-wave to a tolerable level for the relay RE.

Finally, the diode D 2 serves as a well-known protection against high cut-off induction voltages, which could endanger the thyristor TH. It also supports arousal during the negative half-wave, as it has a decay delay. Instead of the in Figure 4 used thyristor TH, a transistor Tr can also be used.

Claims (4)

Circuit arrangement for controlling one of one AC mains powered electromechanical relay, characterized in that that the relay (RE) a capacitor (C) is connected in parallel to hold the relay during the negative alternating voltage half-wave when the relay is activated with a in a known way only in the positive half-wave switching thyristor (TH). 2. Circuit arrangement for controlling an alternating current network Powered electromechanical relay according to Claim 1, characterized in that the excitation current of the relay (RE) is limited by a resistor (R). 3. Circuit arrangement for controlling an alternating current network Powered electromechanical relay according to Claims 1 and 2, characterized in that that the excitation of the relay (RE) via a thyristor (TH) or transistor (Tr) he follows. 4. Circuit arrangement for controlling an alternating current network Powered electromechanical relay according to Claims 1 to 4, characterized in that that the St lerstrom for the thyristor (TH) or a transistor (Tr) from one Control electronics (SE) is supplied.