Automatic Transfer Switch - NewMar ventana 2017 Owner's Manual

Automatic Transfer Switch

Interior view of a Transfer Switch
Main Service Panel Breaker Box
The main service panel or 120 Volt breaker box is typically located inside a bathroom, bedroom, or front overhead cabinet
depending on the coach model and floor plan. The breaker box contains the main 50 Amp (or 30 Amp if equipped)
breaker and the individual breakers protecting each circuit from overload conditions. Any unit equipped with two air
conditioners or more must have 50 Amp service. The task of the breaker is to "trip" if the current exceeds the amperage
rating on the breaker to prevent damage to the wiring of the circuit.
The breakers are resettable by simply flipping the breaker to the 'off' position, and then back to the 'on' position once the
overload condition is removed. All 120 Volt circuit breakers are located in the main service panel unless the coach
is equipped with an inverter/charger. These units are also equipped with a subpanel.
Breakers positioned next to each other are on different poles in a 50 Amp panel. If only part of the electrical
circuits are working, you may have a poor connection at shore power. In this instance, power is most likely
only being provided to one pole or leg.
Subpanel
The subpanel is a smaller 120 Volt breaker box containing the breakers for the circuits which the inverter is wired to
power. It is typically located near the main breaker box unless the coach is equipped with an Energy Management
System (EMS). In this case, the subpanel is often located within the EMS panel. The subpanel is installed to limit the AC
power use to specific circuits when the electricity is supplied by the inverter. Some inverters may be used to power a
specific circuit. In this case, a subpanel is not used.
50 Amp Energy Management System (EMS)
The 50 Amp Precision Circuits Energy Management System is currently offered as standard equipment on all Canyon
Star, Ventana, and Dutch Star coaches. Its function is to provide power management for certain 120 Volt loads and as a
system of energy management to minimize the overloading and tripping of circuit breakers. The EMS contains a main
distribution panel with a self-contained control module and a remote display panel, which is typically located in the dash
overhead electrical control cabinet.
The EMS control module automatically senses the available power being supplied to the coach. The module determines
whether it is connected to a 50 Amp (240 Volt) or the generator. On 120 Volt service, it is unable to determine if the
source is providing 30, 20 or 15 Amp shore power. Depending on available power, it can control up to seven loads. The
EMS controls air conditioner loads using low-voltage switching and other 120 Volt, heavy-load appliances, such as block
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Current coaches with a generator will also have a transfer switch installed in the cord
compartment. An automatic transfer switch converts two inputs and connects them to a
single common output. The shore power cord is connected to one of the inputs, while
the generator is connected to the transfer switch's second input.
Automatic transfer switches are logic-controlled to convert under a given set of
conditions. The transfer switches used in RVs are typically generator priority switches
which connect to shore power under normal use. As soon as the transfer switch detects
the presence of 120 Volt power on the generator input lines, it will switch over to the
generator's inputs and drop the connection to shore power.
Transfer switches are designed so that only one input can be connected at a time in
order to prevent any back feeding of electrical power. In addition, RV transfer switches
generally have a built-in delay allowing the generator to warm up and speed up before
actually switching the load. This prevents stalling or stumbling while the engine is still
cold and not producing full power.