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How Does an RV Automatic Transfer Switch Work?

how does an rv automatic transfer switch work

An automatic transfer switch (ATS) serves as the brains of your electrical supply for your RV. It automatically controls the flow of electricity from the main electrical utility or your generator. Once power outage is detected, it switches the power source from the generator and does the same when power is given back to the electric panel.

More of these theories are entailed in this article. This is a great way to begin understanding the mechanics of how an ATS works and expand your electrical knowledge about your RV facilities.

How Does an RV Automatic Transfer Switch Work?


Automatic Switching of Electric Supply

ATS readily responds to a power outage by activating a secondary supply from the generator. The generator is in standby mode, which can convert mechanical energy from in-house turbines and combustion engines to electrical power. After switching, the generator then operates in full load until enough power is available back at the main panel.

The ATS is connected to both the main electrical utility and generator such that when a fault is detected, switching happens automatically letting one supply source to operate at a time. It goes by the steps of contact the power sources to connect and disconnect and initiate transfer mechanisms between the supplies.

Start-up and Switching Time

According to Agbetuyi (2011), generator start-ups usually take 1.5 to 2 seconds to actualize. This is called the Time Delay Engine Start (TDES). ATS, then, makes sure the generator reached the desired voltage and frequency to operate. In some cases, additional time is required to start up called the Time Delay Normal to Emergency (TDNE). TDNE is also the equivalent time used to switch the power supply back, once the main panel achieves operating power.

After switching, the system then allows cool down for the engines attributed to Time Delay Cooldown (TDC). TDNE and TDC both contribute to the delay of operations and power capacities, which should be accounted in prior.

To read more about these concepts, an integrated content is relayed by CAT.

Monitoring of Load from Power Sources


ATS also incorporates supplementary circuit components that monitor the power status of the sources. In the circuit, an intelligent logic control system consists of contractors for relays and accessories for safeguarding. These make sure information is continuously fed to the brain and messages are relayed to the switching mechanisms readily.

The monitoring is based form the single-phase line from the generator and the utility, and readily checks the availability of power from either source. During the operation period of one power source, it checks the condition of the other power source from time to time. Inspection points include spikes in voltage, power surges, or plummeting leading to brownout.

The ATS system

In order to synchronize the switching and monitoring functions of ATS, there are four blocks identified: relay switching, timer relay, contractor switching, and digital multimeter. The relay switching serves as the voltage monitoring station with the relays acting as sensors for spike and surge sensing. Other relays give delay to the sources to provide spaces for initiation and energization.

Contractors, on the other hand, bridges the supply from one source to another while the multimeter helps in gauging the output voltage, current, and frequency of the power sources.

More of these concepts and visualization are relayed in the “Design and Construction of an Automatic Transfer Switch for a Single Phase Power Generator” by Ayoade Agbetuyi.

Protection from Overload

Switching takes only seconds to take place, and it is the best interest of the system to protect itself from overloads or sudden plummeting. Switching, then, is deemed as a critical step in the power system, so the provision of safeguarding to the utility and the generator set is important. In this regard, unit size is essential to be considered in the selection, such that it works proportionately as a protective component to the supplementary power sources.

You can find a wealth of various ATS in Amazon for your RV. Among these are the Progressive International ATS, Pavlysh Power Inverter, and AIMS Power Inverter. These come in different current and voltage supply.


An automatic transfer switch (ATS) is an important component of your RV power systems. It serves as an automatic switching power controller between your electric utility and generator, monitors power supply, surges and fluctuations, and acts as a protective part of your system from sudden overload.

Make sure to check popular finds in Amazon and ensure the compatibility of the component to your current power sources prior to installation for optimum RV protection.

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