about perfect for a 30 amp RV!
Hi, A buck/boost autotransformer? https://www.larsonelectronics.com/product/223930/1-phase-buck-boost-step-up-transformer-113v-primary-120v-secondary-31-25-amps-50-60hz Add some surge protect...
Forum Discussion
Hi DrewE,
The information about the Magnum having an autoformer inside, is what a Magnum repair location told me. Whether it is true or not is quite another matter. I do know that load support is NOT voltage support. I do know load support is a feature I find extremely useful.
I do also know that the Magnum will NOT operate on some GFCI outlets, but works just fine on others. I've had this happen at the same house--where one gfci worked and the other blew immediately. Because of my "patch board" approach I can wire around the Magnum in 20 seconds. The RV by itself never trips a GFCI.
Sometimes the Magnum does not allow low voltage shore power to connect. It clicks, drops the power, and repeats. Turning on the inverter does not solve this issue.
I ran into another anomaly recently at a brand new parking lot. I verified there was power, plugged in the Magnum and it would not connect to the shore power. Usually there is a short delay and then the Magnum transfer switch clicks in. When I wired around--power was available.
In inverter mode, (i.e. no shore power) Magnum does NOT recommend running a roof air conditioner.
A serious design flaw is the cooling fans are 120 volts. So if you shut down the inverter when there has been a heavy load, the unit may catch on fire. DAMHIK. To be fair Magnum did replace it under warranty. But it would have been so easy for them to have the fans as 12 volt DC.
All in all, if I ever have another "kick at the can" I'll purchase a Victron.
The information about the Magnum having an autoformer inside, is what a Magnum repair location told me. Whether it is true or not is quite another matter. I do know that load support is NOT voltage support. I do know load support is a feature I find extremely useful.
I do also know that the Magnum will NOT operate on some GFCI outlets, but works just fine on others. I've had this happen at the same house--where one gfci worked and the other blew immediately. Because of my "patch board" approach I can wire around the Magnum in 20 seconds. The RV by itself never trips a GFCI.
Sometimes the Magnum does not allow low voltage shore power to connect. It clicks, drops the power, and repeats. Turning on the inverter does not solve this issue.
I ran into another anomaly recently at a brand new parking lot. I verified there was power, plugged in the Magnum and it would not connect to the shore power. Usually there is a short delay and then the Magnum transfer switch clicks in. When I wired around--power was available.
In inverter mode, (i.e. no shore power) Magnum does NOT recommend running a roof air conditioner.
A serious design flaw is the cooling fans are 120 volts. So if you shut down the inverter when there has been a heavy load, the unit may catch on fire. DAMHIK. To be fair Magnum did replace it under warranty. But it would have been so easy for them to have the fans as 12 volt DC.
All in all, if I ever have another "kick at the can" I'll purchase a Victron.
DrewE wrote:pianotuna wrote:
Hi,
Except that every hybrid inverter/charger (those with load assist) has an autoformer inside.DrewE wrote:
This makes good sense; if an autotransformer were used in a converter, you'd end up with a neutral/ground fault by design in the RV, and also significantly increase the risk of a hot skin condition. on the RV.
Are you sure about that? The manual for the Magnum hybrid inverter/charger states that "The AC output neutral conductor and the DC negative conductors are not connected (bonded) to the inverter chassis. Both the input and output conductors are isolated from the enclosure and each other." If there is an autotransformer in the circuit, it is not bridging the AC and the DC sides (i.e. there's some other means of providing isolation). I would guess it's instead a normal transformer with separate windings, but I really don't know anything of the details of their circuit topology.
It's entirely possible to make a voltage boosting transformer that is not an autotransformer; it just typically requires more copper or whatever metal is used for the windings and generally a larger core and so is bigger, heavier, and more expensive.
