I have a client that has burnt up their brake chopper resistors twice in the last few weeks with the drives idle but the disconnects on. The difference is that their co-gen turbine has been having regulation problems. My theory is that the co-gen is outputting a high ac line which is being converted to a high DC bus. I think that the high DC bus is then causing the choppers to pump the energy to the resistors and cooking them.
These are around 100hp drives, so they have the SCR pre-charge, but I don't think that a high line would inhibit the pre-charge from turning full on. I don't think that there is a way to stop this from happening except to make sure the disconnects are open when the turbine is fired up. They want to wire the resistor thermos to the drives, but I don't think that this will do anything either as I don't think the drive has the capacity to turn off the pre-charge on demand.
These are really old drives and I'm having a hard time just finding documentation on them. Fun stuff.
These are around 100hp drives, so they have the SCR pre-charge, but I don't think that a high line would inhibit the pre-charge from turning full on. I don't think that there is a way to stop this from happening except to make sure the disconnects are open when the turbine is fired up. They want to wire the resistor thermos to the drives, but I don't think that this will do anything either as I don't think the drive has the capacity to turn off the pre-charge on demand.
These are really old drives and I'm having a hard time just finding documentation on them. Fun stuff.