More than an Overload

In our last post we touched on SubMonitor and its capabilities. Over the next several weeks, we’ll take a closer look at SubMonitor and what a critical role it can play in protecting a 3-phase installation.

Before we get into the details of SubMonitor and all of its capabilities, let’s look at it in the context of overloads in general. Although SubMonitor offers far more protection than just as an overload, it functions primarily as an overload.

Overloads, the Basics:

Overloads play an important role in protecting submersible electric motors from overheating. There are two primary conditions that cause a motor to overheat and fail: a lack of cooling flow past the motor, and high current (amp) condition. While the first condition is straightforward, a high current condition may be caused by several factors including low voltage, high voltage, a ground fault, or an imbalance in a 3-phase system. Regardless of reason, power needs cut when the motor overheats. The type of protection used dictates motor survival; if you’re using the wrong overload, the motor won’t survive.

Overloads for all Franklin Electric submersible motors must be Class 10, Quick Trip, meaning it must take the motor off line within 10 seconds of the motor reaching five times service factor amps. These overloads must also be ambient compensated. That is, they must trip consistently at the same value regardless of the ambient temperature.

Overloads and Franklin Electric:

In the case of Franklin Electric single-phase submersible motors, Franklin Electric always supplies the overload, either in the motor itself or in the control box.

With Franklin Electric 3-phase motors, however, a 3-phase panel is needed with the required overloads inside the panel. These overloads need to be specified and supplied by the installer or electrician.

The most basic type of 3-phase overload is what’s called a heater. These are the oldest and most conventional. As current increases in the overload, the “heater” causes a bimetal contact to bend, thereby opening the circuit.

Moving up in sophistication is generally what’s known as adjustable solid-state overloads, such as the ESP100. A caveat on these products is that they must be set to full load amps, not service factor amps. (These values can be found in the AIM Manual starting on page 22.)

Despite motor type, if you are working with a 3-phase system, all the work of picking the right overload is done for you on page 29 of the AIM Manual. Here, you will find the proper Class 10, Quick Trip overloads, both heater- and adjustable-type.

SubMonitor – More than an Overload:

Now that we have reviewed overloads and their functionality, we can look more deeply into what sets SubMonitor apart from typical overloads.

While SubMonitor is an overload, it’s also more. The SubMonitor offers flexibility unavailable in other protection devices. Using the default settings that are already in the unit, it can be very simple and basic to install and set-up. But, if you need a customized set-up for an installation, SubMonitor offers a great deal of flexibility and even more protection

Join us next week as we start a series on the SubMonitor and all that if offers in system protection.