Topic: Surge Guard (Technology Resource Corporation)
Presenter: Owen Jackson
[This course covers basic electrical systems; and hazards you'll encounter on the road...It's geared to Country Coach motorhomes, but much of this information is of broader general interest to RVers.]
Today's coaches are absolutely loaded with electrical systems -- not just the appliances, but all sorts of circuit boards that run the many and varied complex system in today's RVs. They all need to be protected. In the US we do a pretty good job of generating power. ANSI standards results in the need for electrical systems to operate efficiently between 102 and 132 volts. But for various reasons where we plug into shore power we're subject to conditions that are outside of the limits of our onboard electrical components, creating serious risks of damage. Surge Guard is intended to protect against all types of the risks we encounter on the road.
Coach systems are referred to as four wire 120/240 volt systems, 50 amps. The "four wire system" refers to 4 wires coming into the coach: Green is ground; white is neutral; black is a hot wire; and white is a hot wire. So there are two separate 120 volt systems, each capable of 50 amps. This provides in effect 100 amps of power for the coach, which is balanced and distributed to each side of the coach. A 30 amp source offers three wires in. Both "sides" of the coach will have 30 amps available. Thus 50 A connections really offer 100 amp potential to the coach; while a 30 A connection only delivers 30 amps -- a 70 amp difference between the two types of connections.
Open neutral problem: You lose phasing in 50A system, and it will provide 220 volts -- which will fry your appliances. This is protected against by the Surge Guard.
Spikes and Surges problem: Caused by tranformers, change in loads, grid management, etc. Basically outside of normal AC sine wave. The Surge Guard will absorb the surges and spikes (excessive peaks and toughs of the wave amplitude) before the power enters your coach. These things happen in nonoseconds, and are extremely distructive of anything electronic. The destruction is incremental, and happens over a longer period of time. Your failed microwave may have been the result of an RV using (unprotected) "bad power" over time.
Over and Under Voltage: Two types of loads. Inductive load is anything with a winding -- e.g. electric motors and microwaves. Resistive loads (like lights or batteries) don't care that much about voltage. If you run your air conditioner (inductive load), and voltage drop, amperage goes up, and that causes heat which can burn up a motor. Safe range is 102-132 volts. Surge Guard monitors both shore power and generator in CCs, except where there is an autostart on the generator. If you're at 104 volts (theoretically okay) and you turn on the air conditioner, the voltage will immediately drop to perhaps 95 volts -- which could damage air conditioner. However Surge Guard will shut it down before it can be damaged..
The Surge Guard unit has a red light for each of the two lines in. They're illuminated when you have power coming into the Surge Guard. Lower left light will be blinking -- for 2 minutes 16 seconds, while it performs a diagnostic check on the power source. If it finds a bad power pedestal, lower right light will illuminate. The blinking light means only voltage okay and you're in the timeout mode.
The key switch is for emergency bypass. It will bypass over and under voltage. When you do bypass, you take out over and under voltage protection. Under that situation do NOT run inductive loads -- microwaves, air conditioners, etc (anything with a motor). But you CAN run resistive loads such as lights and charging up your battery.