If several windows or several shades are to react to the same operation command and move in parallel, they can be operated together at one drive output of a control system. Therefore, it must be noted that not all drives are suitable for being connected in parallel to one clamp.
Are the drives suitable for parallel connection?
It must first be checked whether the motors that are to be used are intended for parallel connection by the manufacturer. This information can be found in the data sheet of the motors, in case of doubt ask the manufacturer.
If the motors are suitable for direct parallel operation, they can be connected together at the control output. For motors that are not approved for parallel operation, an external group control relay is required.
What does a group relay do?
A group control relay prevents disturbing travel back and forth shortly before reaching the end position and protects the drives from damage. The technical background for this is as follows:
Actuators which are not intended for parallel operation by the manufacturer usually have four connections: PE (protective earth), N (neutral conductor), up and down. During "up" travel, 230 V AC voltage is now applied to the "down" connection (opposite direction). This leads to the following behaviour:
If two motors connected in parallel travel in one direction, they will never reach their end position exactly at the same time. Motor 1, which first reaches its end position, switches off. However, if motor 2 is connected in parallel, then motor 1 receives current from motor 2 in the opposite direction. This means that motor 1 reverses again in the opposite direction.
As a result, the motors move up and down shortly before the end position until both have reached their end position. This is not only annoying because it may take a long time for the windows or shades to reach their final position - it also damages the drives.
The group control relay solves the problem by disconnecting the connection of the opposite direction to the neighbouring motor. This is why these useful helpers are also called isolating relays. The motor that reaches the end position first stops and is no longer influenced by the motor connected in parallel.