1. An Automatic Change Over Switch ( ATS) can be designed to monitor incoming voltage levels for public utility power (MAINS). This is to ensure that the amount of voltage that comes from your mains supply source (NEPA/PHCN in Nigeria for instance) is good enough for your apartment/office or equipment. It protects against over-voltage or under-voltage entering into your electrical loads or equipment. This can not be compared to your MTS that will just transfer any voltage ether low or high from the incoming power source power source to your building/office or sensitive electrical equipment.
2. An ATS is helpful in situations when for instance, your manual changeover switch is installed at the meter board under the staircase of a storey building and you live on the third floor. Anytime Mains fails, you would have to come down stairs to change over to your generator. and this the same case when Mains is restored. The stress of constantly climbing up and down both to manually change over and start or stop your generator can be minimized by the use of an ATS for automating the process without the need for human intervention.With a Manual transfer switch (MTS) installed, the case is made worse when you need to come out in the middle of the night to operate your generator or to changeover, more so, under the rain.
3.With an MTS, you suffer inadequate sleep. This is because your MTS cannot automatically stop your generator when Mains is restored. so, while going to bed with your Generator running, you can only sleep with one eye closed because you need to know when mains is restored so as to get up to turn off your Generator otherwise you will be burning precious fuel away even while mains is available. An ATS in this case will automatically transfer power (Change over) as well as shutdown your generator when mains is restored while you enjoy your sound sleep.
An MTS can only change over, nothing else. However, an ATS can have a myriad of standard and customized extended functions built in. examples of extended functions include:
A.Monitoring the inverter battery voltage levels. This makes the ATS starts the Gen automatically when inverter battery voltage levels are low.
B.Generator scheduling function which schedules your Generator to run at specific periods of the day much as you can as well preset how long (duration) you want the Gen to run before shutting down automatically.