Using the immediate drop after the load was turned on, I get the following results:
For 5.5A the load regulation is 0.365% and for 2A it is 0.0517%
(The manual specifies a load regulation of 0.02% + 3mV)
There is also a note where it states this is "Against 0 - 100% change of output current) -- what does this mean?
Are you measuring at the output binding posts (spade terminals work well for this)? At 5.5A, any length of conductor will drop additional voltage, something the power supply can not correct for. Does it make a difference if you change the load so the current is only 5.4 A. Could be that the current limit is starting to kick in (probably not, since it is already out of spec by 2A). I do not believe this power supply has output terminals on the back or options for remote sensing, so if you are measuring at the binding posts and make sure you are below the current limit, it sounds like the power supply is out of spec. Could be a filter capacitor that is dried out, causing the pass transistor to drop out at high currents.
0% to 100% change of output current refers to the maximum rated current, i.e. from 0 A to 5.5 A for this particular model. It is just written that way so they can use the same spec for multiple power supplies with different voltage/current ranges.
I was thinking that instead of replacing the power cord with a three wire mains cord that I simply chop off the plug of the existing cable and install a three prong one (while ensuring the wire attached to hot goes to the fuse/switch). I believe the standard practice is that the hot goes to the fuse/switch, correct?. Then I would run a separate ground wire from the three prong plug to the outside of the case to ground it.
Yes, hot to switch is correct. I am not sure about what relevant standards say about running the ground connection separately, but in general the design should be that the live/neutral wires should disconnect before ground does. In a plug I leave the ground wire longer so it will not get pulled out first. I do not think running a wire alongside the mains cord would meet this standard. I would just remove the current mains cord and replace it with a three wire cord with molded three-prong plug. You could even cut the IEC 60320 connector off a computer power cord and use that, assuming it fits through the strain relief. But do not use one discussed in
this thread .