*All measurements are made with a voltage divider circuit to cut the voltage into 1/3 of the value and observed with an oscilloscope. The voltages below have all been multiplied by 3 to give the actual voltage.
So I have a 3 phase setup with the following characteristics (this is a very old machine):
*Voltage readings taken from phase to earth ground (no neutral line is available from the transformer, is this a problem?)
Frequency: 60Hz
Phase A: 231V +27V DC offset
Phase B: 234V +24V DC offset
Phase C: 231V +15V DC offset
These three phases are being full wave bridge rectified to DC and the output has the following characteristics:
Max: 440V
Min: 370V
Delta: 70V
Frequency: 360 Hz (doesn't this seem high?)
So we have an electrolytic capacitor bank of 40uF 600V 85 degC tied to this output (and .1 uF biasing caps to earth ground on - and +) along with some kind of control circuit (it is impossible to determine what this load is but it does sink a good amount of power) when these readings are taken and this bank has failed multiple times in the past. My question is, would this frequency and delta combination cause the electrolytic capacitors to fail? Could they just be overheating from this combo? They blew out at the cathode and melted the insulation around that area last time.
The other strange part of this is that sometimes one or more of the 30A phase fuses will pop, making me believe its the load's issue but I could be wrong.
Note it is impossible to run this machine without at least 20uF of capacitance across the DC output and the load must stay attached. I do not currently have an ammeter capable of this load rating.
So I have a 3 phase setup with the following characteristics (this is a very old machine):
*Voltage readings taken from phase to earth ground (no neutral line is available from the transformer, is this a problem?)
Frequency: 60Hz
Phase A: 231V +27V DC offset
Phase B: 234V +24V DC offset
Phase C: 231V +15V DC offset
These three phases are being full wave bridge rectified to DC and the output has the following characteristics:
Max: 440V
Min: 370V
Delta: 70V
Frequency: 360 Hz (doesn't this seem high?)
So we have an electrolytic capacitor bank of 40uF 600V 85 degC tied to this output (and .1 uF biasing caps to earth ground on - and +) along with some kind of control circuit (it is impossible to determine what this load is but it does sink a good amount of power) when these readings are taken and this bank has failed multiple times in the past. My question is, would this frequency and delta combination cause the electrolytic capacitors to fail? Could they just be overheating from this combo? They blew out at the cathode and melted the insulation around that area last time.
The other strange part of this is that sometimes one or more of the 30A phase fuses will pop, making me believe its the load's issue but I could be wrong.
Note it is impossible to run this machine without at least 20uF of capacitance across the DC output and the load must stay attached. I do not currently have an ammeter capable of this load rating.