Would appreciate advice on the best portable surge protector for a 30 amp service. We're going camping at a park that has occasionally had voltage drops. Wouldn't that damage things as well? Don't want have a permanent wired protector since some of us(I won't say who) have this tendency to change motor homes.
J

if you're worried about voltage DROPS, rather than SPIKES or SURGES, you're looking a large device priced a few hundred dollars -- essentially like a UPS.
Brownouts are poison for refrig compressors and some motors, but not lighting.

Something like a Hughes Autoformer

quote:

Originally posted by Jim and Tere:
Something like a Hughes Autoformer

Yes, which gets excellent reviews on Amazon, I see

Does anyone have a Hughes Autoformer and, if so, will you share your experience? From what I have read, low voltage at campgrounds is a common problem. As I understand it, some surge protectors will turn off your system if they sense either a surge OR a drop in voltage and turn the system back on when the voltage is withing acceptable limits. But, if the system is off and you're in hot weather, and the system stays off, you're in a little bit of a problem. Example: Next weekend, we're going to Huntsville, Alabama for three days. Our dog will be with us. If the system goes off and stays off, we'll have a dog that might be dead. So, I'll have to hire one of the campground attendents to check on our RV and call us if the voltage drops to a level that turns everything off. The campground is known to have low voltage problems. There are no alternative campgrounds.

Good morning, Jim and Tere;

For the "Surge Guard" device, if you like that particular brand (TSC) look at their Model 34830 plug-in portable device. It is on sale at Camping World right now for about $215. This device will drop out automatically, and then reset when the voltage comes back into the nominal voltage range that it allows. There are some other makers who have very similar devices.

Instead, if you are going to go with a voltage regulating transformer, I would look at something like a 2000 Watt or 3000 Watt Sola CVS Series Constant Voltage Transformer. This a three winding device with a "ferro-resonant" third winding "buck-boost" section that will automatically control the 120 V AC voltage at a very close value over the range of about 90 V AC to 140 V AC input range, and it does it completely automatically for both low voltage and high voltage.

The minimum that I can suggest is the 2000 Watt. I think that it might start one rooftop mounted air conditioner. I am sure that the 3000 Watt rated one will start a rooftop mounted air conditioner. The only problem with a constant voltage transformer, just like the Hughes AutoFormer, is the weight. You will need to see if you have sufficient reserve weight carrying capability so that you will not exceed the GVWR for your motor home or the axle that may be carrying most of the weight. The "ferro" in that "ferro-resonant" does indicate that there is iron in the lamination stack or core. The 3000 Watt unit will be well over 100 pounds

And there are other makers who also make constant voltage transformers, such as the Square D Company under their Topaz label. I have only one Topaz 1000 Watt transformer, but over the years I have used many Sola CVS transformers up to 5000 Watts, and they have been very reliable and functional when their maximum current rating is not exceeded. For starting an inductive load such as an air conditioner, it would be prudent to get the biggest one you can carry.

For the best performance, I would put the 34830 into the power source (the RV Park electrical pedestal power source), and then to to the constant voltage transformer. The Surge Guard will drop out just about at the same voltage that the constant voltage transformer will no longer be able to keep the voltage at the regulated point. They will be compatible and complementary. The only thing that might be of concern is that the 34830 will wait until the line voltage has come back up to 108 volts AC before it resets from a low.

Enjoy;

Ralph
Latté Land, Washington

Nicely said. One consideration for the larger Sola units is that to maintain power output, the input current would have to increase (if I understand the graphs correctly), and the internal resistance and hysteresis losses would come into play, meaning that, in short (pun intended) the larger Sola units could overload the pedestal receptacle breaker.

Those considerations would lead me to choose the TSC for being cheaper, lighter, portable, and simpler (although the Sola's 25 years MTBF is impressive. Virtually all 120VAC appliances on an RV are designed to handle under- and overvoltages. My Atwood A/C is claimed to tolerate 92-130V, and it's the most sensitive.

Surges and spikes would be my biggest concern.

Our late friends Lenny and Judy told of a lightning strike in New Orleans that wiped out the entire electrical system on coaches on both sides of them, but Lenny had a big protector and though it got fried, the coach suffered very little damage. A few hundred bucks is a lot less than every thing electric in your coach!