Internet PLC Forum

General => Technical support => Topic started by: Don J. on October 13, 2004, 10:41:02 AM

Title: AC vs DC power supply
Post by: Don J. on October 13, 2004, 10:41:02 AM

The installation instructions for the T64H-Relay calls for a 12-0-12 AC input which the PLC converts to 24 VDC.  I want to install this into a panel that already has regulated 24 VDC available.  Can I use 24 VDC to power the PLC or must I add another transformer.  TIA

Don

Title: Re:AC vs DC power supply
Post by: support on October 17, 2004, 10:36:51 PM

The T64H PLC assumes an AC transformer is available with center-tap. This is unique only for
T64H-Relay and does not apply to all other PLC models. (This PLC started life as a customized design and that's why it has an "odd" power supply requirement).

You could actually use a 24VDC power supply to power the PLC if you provide a "center tap". You could emulate this by connecting two 5W, 100 Ohm resistor in series as a voltage divider.  This form a 0, 12 and 24V power supply can hence can be used to power the T64H-Relay. It is not very efficient in term of energy use since the voltage divider draws 0.12A at all time on top of the current required to drive the PLC.