Transformer Readings
Posted: Fri May 27, 2011 1:37 pm
Regarding the DC servo power supply for 110VAC service, JM wrote:
The supplied transformer is not an autotransformer. That is, the secondary windings are not directly connected to any of the primary windings. Therefore the secondaries will "float" with respect to ground, unless you deliberately ground one side or the other of each secondary winding (making it a neutral). As long as the secondary voltage is only used within the confines of the control cabinet, a grounded neutral is not required.
The only meaningful voltage measurements, then, are between matching secondary wires.
What AC voltage do you measure between Green and Green? It should be approximately 85VAC.
What AC voltage do you measure between Blue and Blue? It should be approximately 24VAC.
Since you give four separate measurements, I am guessing that you are measuring AC voltage from each secondary wire to chassis ground.When I connect the transformer as shown on the diagram I am getting secondary voltage readings as follows:
Green 43
Green 31
Blue 35
Blue 15
The supplied transformer is not an autotransformer. That is, the secondary windings are not directly connected to any of the primary windings. Therefore the secondaries will "float" with respect to ground, unless you deliberately ground one side or the other of each secondary winding (making it a neutral). As long as the secondary voltage is only used within the confines of the control cabinet, a grounded neutral is not required.
The only meaningful voltage measurements, then, are between matching secondary wires.
What AC voltage do you measure between Green and Green? It should be approximately 85VAC.
What AC voltage do you measure between Blue and Blue? It should be approximately 24VAC.