Valve actuators specialist Sipos Aktorik has successfully addressed the problem of synchronising valve stems, using a master actuator to reflect control signals from a PLC to slave devices via a 4—20mA loop.
Traditionally, a mechanical system links two gearboxes to one actuator, but when stems are a considerable distance apart there is a problem.
Sipos Aktorik's system ensures that control information is received simultaneously, with the system checking itself at two levels.
At the first level, if deviation is larger than a programmed value, the system generates a 'slow' signal, while at the second it transmits a 'stop' signal. That avoids mechanical problems, such as side loads, causing a problem.
