Can more than one MS41-7153 actuator be paralleled when being driven by a MNB series controller?
TAC I/A Series, Field Devices
MNB series controller
Several MS41-7153 actuators controlled by a common signal.
Series of parallel dampers are to be controlled by the same control signal.
Yes several MS41-7153 actuators can be driven by the analog output from a MNB series controller.
There are two acceptable methods of providing parallel control.
1. Control the first actuator using either the voltage output or current output from the controller and cascade control from the feedback AO of one actuator into the AI of the next actuator. The AO of the last actuator should be routed back to the controller to provide feedback confirmation of the damper operation. In this way should any damper fail, the feedback will indicate that one (or more) of the actuators did not drive to the desired position. Using this method there is theoretically no limit to the number of actuators that could be driven from one controller AO output. When controlling a series of actuators in this manner, you must make sure that the power to the actuators are phased correctly, especially if using more than one transformer.
2. Alternate method for use with four or less actuators. Up to four actuators may be driven using the 4-20 ma drive from the controller. The 500 ohm resistor should be connected across the actuator wired closest to the controller. When using this method, and more than two actuators are being parallel controlled, the resistance of the parallel resistor may need to be increased slightly or the drive signal may need to be increased by as much as 2.5% to make up for the parallel resistance effect of the 80 k-ohm input impedance of the actuators.