Hello all
I'm new to this forum. This is my first post and hoping I can get some help.
I've been working on this piece of equipment with 8 capacitors in a bank. It's on the front end of the equipment and forms a voltage doubler network. There are 4 caps on the +ve rail and 4 on the -ve. It's powered from the utility mains of 208VAC-240VAC.
The problem is that the equipment is exhibiting a rather large in-rush current with keeps popping the input fuse.
After testing all of the caps with a Sencore LCR103 meter, I've found that all of the caps on the -ve Bus are showing a negative ESR on the meter.
I've built a very simple model of the circuit and simulated it with LTSpice. The simulation confirms that with a negative ESR on the caps, the in-rush can indeed be extremely large. The simulation showed inrush in the range of teraAmps.
These are Hitachi caps with the following specs:
Cap Value: 8200uF
Voltage: 400VDC
ESR: 18mΩ
Lser: 40nH
Leakage: 0.01CV or 5mA (whichever is greater)
When the caps are tested, the 4 on the -ve rail are showing ESR's of -0.05Ω, -0.26Ω, -0.15Ω and -0.35Ω. The caps on the +ve Bus are averaging 0.30Ω.
I've googled on this but did not find anything. Any idea what a -ve ESR means and what effect it can have on circuits?
Thanks in advance.
I'm new to this forum. This is my first post and hoping I can get some help.
I've been working on this piece of equipment with 8 capacitors in a bank. It's on the front end of the equipment and forms a voltage doubler network. There are 4 caps on the +ve rail and 4 on the -ve. It's powered from the utility mains of 208VAC-240VAC.
The problem is that the equipment is exhibiting a rather large in-rush current with keeps popping the input fuse.
After testing all of the caps with a Sencore LCR103 meter, I've found that all of the caps on the -ve Bus are showing a negative ESR on the meter.
I've built a very simple model of the circuit and simulated it with LTSpice. The simulation confirms that with a negative ESR on the caps, the in-rush can indeed be extremely large. The simulation showed inrush in the range of teraAmps.
These are Hitachi caps with the following specs:
Cap Value: 8200uF
Voltage: 400VDC
ESR: 18mΩ
Lser: 40nH
Leakage: 0.01CV or 5mA (whichever is greater)
When the caps are tested, the 4 on the -ve rail are showing ESR's of -0.05Ω, -0.26Ω, -0.15Ω and -0.35Ω. The caps on the +ve Bus are averaging 0.30Ω.
I've googled on this but did not find anything. Any idea what a -ve ESR means and what effect it can have on circuits?
Thanks in advance.