Room temperature can be controlled by using multiple A/C fans. The following is an example of using the UT55A Digital Indicating Controller with its ladder sequence function to control the operation of multiple A/C fans.
- Run multiple A/C fans to lower the room temperature in the hot summer months.
- Need to prevent all fans from running at the same time because the inrush current trips the breakers
Yokogawa's proposed solution
Figure 1. A/C fan startup control
With 8 A/C fans
The UT55A can come with up to 8 alarm outputs that can control the fans. Ladder sequencing is build in, allowing you to use a timer or other such function to set up a time delay on each output.
* Ladder programs must be created on the LL50A Parameter Setting Software and loaded onto the UT55A.
- Set the setting (SP) value to the temperature at which you wish the fan to turn on (e.g. 23°C).
- Set alarm outputs 1 through 8 so that the 8 fans will turn ON when the room temperature reaches the SP value.
- Set a delay (of 5 seconds, for example) between alarms so that all fans do not turn on at the same time.
A single UT55A can automate startup of multiple A/C fans—lowers wiring and components costs and saves space (timers and compact PLC's no longer necessary).
The LL50A Parameters Setting Software is designed to build and set parameters, ladder programs, and the like of the UTAdvanced digital indicating controllers from a PC. The tuning and monitoring of ladder programs are possible during communication with the controllers.
The UT55A and UT52A temperature controllers employ an easy-to-read, 14-segment large color LCD display, along with navigation keys, thus greatly increasing the monitoring and operating capabilities. A ladder sequence function is included as standard. The short depth of the controller helps save instrument panel space. The UT55A/UT52A also support open networks such as Ethernet communication.