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SubMonitor: Protection Flexibility

In our last post, we started a series on SubMonitor. By way of a quick review, SubMonitor is one of the three types of overloads used for 3-phase submersible installations. The three types are heaters, adjustable solid state, and electronic. SubMonitor falls into the last category and although SubMonitor is classified as an electronic overload, it offers far more than simple overload protection. In the next few weeks we’ll take a look at all the capabilities and flexibility SubMonitor offers.

All overloads for Franklin submersible motors must be Class 10 Quick Trip. This means they must take the motor off-line within 10 seconds of the motor reaching five times service factor amps. Overloads must also be ambient compensated, meaning they must trip consistently at the same overload value regardless of the ambient temperature. Ambient compensated overloads must always be used when the motor and the overloads are in different locations and therefore at potentially different temperatures. In the case of a submersible installation, the overloads are in the panel above ground and the motor is obviously submerged underwater. As a result, they will be at different temperatures and hence the need for ambient compensation.

Continue reading

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.

 

Even More System Protection: SubMonitor

While Pumptec and its extended family are great options for protecting single-phase systems from adverse conditions, what kind of protection is offered for three-phase systems? This week’s Franklin AID will answer that very question.

SubMonitor is designed to protect any three-phase motor rated from 3 to 200 horsepower (5 to 350 amps). SubMonitor protects submersible and aboveground systems from conditions such as low-yielding wells, pump damage, clogging, bound pumps, and power mishaps, which can be the result of overload, underload, high and low voltage, phase loss and reversal, rapid cycling, false start, or overheating. Continue reading

Pumptec’s Extended Family

In our last post we discussed Pumptec and how it protects single-phase submersible systems from damage. The protection doesn’t stop there, however. Franklin offers two other members of the Pumptec family, specifically designed for Franklin single-phase motors.

QD Pumptec is very much like Pumptec in functionality and how it works, but in a smaller, unique package that quickly installs in a QD Control Box. Using power factor to monitor Franklin 230V submersible motors from ½ to 1 horsepower, QD Pumptec protects against the same adverse conditions as the original: overload, underload, high and low voltage, and rapid cycling. This specific product is often thought of as mini Pumptec because it is designed exclusively to fit inside Franklin QD control boxes.

Also offered in the Pumptec family is Pumptec-Plus. Sometimes called the “big brother,” Pumptec-Plus protects against those same five conditions, but it works with any 230 V single-phase motor ranging from ½ to 5 horsepower. Unlike its Pumptec companions, however, Pumptec-Plus monitors wattage rather than power factor. When watts run 25% higher or lower than operating load, Pumptec-Plus will remove power from the system. We can get a good idea of what our operating watts should be by turning to page 13 of our AIM Manual. Let’s say we are working with a ½ hp, 4-inch, three-wire motor. That motor should operate between a full load of 670 watts and a maximum load of 960 watts.

Since actual running wattage varies by motor, each Pumptec-Plus needs to be calibrated at installation. This calibration allows the Pumptec-Plus to tailor its performance to each specific system so that it can be used with any ½ to 5 hp, single-phase, 230 V motor—even those not manufactured by Franklin.

The system lights on the face of Pumptec-Plus are also an important feature; their color and state (steady vs. blinking) tell you exactly what’s going on with the system. Some installers actually keep a Pumptec-Plus with them as a diagnostic tool. If a problem turns out to be intermittent, they can install the Pumptec Plus and have the homeowner make note of what the lights are doing when the problem occurs.

No matter what type of system you are installing, it’s important to protect your investment. Taking the time to look into protection options can save time and money for you, as well as your customer, in the long run. For more information about how to protect your investment in the field or for troubleshooting help, contact our Technical Service Hotline at 800.348.2420 or hotline@fele.com.

Protect Your System 5 Ways

Last week, we reviewed “drought insurance” for submersible water systems using the Pumptec family of products. This week, we will look specifically at Pumptec and how it protects a system from damage in many other ways.

Pumptec is a microcomputer-based pump protection device that monitors load and supply voltage in single-phase systems. It protects against five conditions that can be dangerous to a motor: underload, overload, high voltage, low voltage, and rapid cycling.

Underload, also known as dry well, includes any condition that leads to the motor becoming “unloaded”. Besides a dry well, this could be an air- or gas-locked pump, failed impellers, a line blockage, or a check valve that is stuck closed. Any of these will cause the motor to unload. Once the unloading reaches a predetermined threshold, Pumptec will remove power from the motor.  Anytime an underload condition occurs, the load light will come on steady and stay on until the reset time is achieved. This reset time can be set from two minutes to four hours, or a manual reset can also be specified.

Overload is the very opposite of underload and can occur when the pump becomes clogged with sand or other debris. If this happens, Pumptec will cut power to the motor and the LOAD light will flash. Unlike an underload, there’s no reset time for an overload condition. Pumptec assumes that it warrants investigation and probably won’t restart. The unit must be manually reset by cycling power to the unit.

In both of these situations the system goes from pumping a normal amount of water to pumping very little or no water. To monitor these conditions, Pumptec uses a threshold point on the power factor curve. As we know from our previous AID, power factor is the relationship between voltage and current. Each motor rating has a unique power factor curve, and thus a unique trip point.

If a motor experiences a loss of water for any reason, the power factor of the motor begins to drop rapidly. When it gets too low (i.e. reaches the threshold), Pumptec shuts off the motor and allows the well to recover. After a predetermined timeout, the system will come back on; however, if the load does not reach or exceed the needed power factor, the system will shut off again. If power factor gets too high, Pumptec will also shut off the motor, but in this case, a manual restart is required. You can see how these power factor scenarios correlate to underload and overload conditions.

As we mentioned earlier, Pumptec not only protects against underload and overload but several other damaging conditions.

High or low voltage can create a multitude of problems for a motor electrically. That’s where Pumptec comes in: to monitor the installation’s supply voltage. If voltage drops below or exceeds 10% of the rated voltage (either 115 or 230 volts), Pumptec will automatically shut down the system.  If the voltage is low, the voltage light will come on and remain steady; if the voltage is high the light will flash.

Rapid cycling is the final condition monitored by Pumptec. Characterized by too many starts in a given period of time, it is most often caused by a failed pressure tank or switch. Because rapid cycling can cause serious damage to an entire system, when it is detected, Pumptec will remove power from the motor until it is manually reset.

It is important to note that because Pumptec monitors power factor, which is a unique measurement for each motor design and rating, this protective device cannot work on just any motor. Pumptec is uniquely engineered and designed to work only with Franklin Electric submersible motors from 1/3 through 1.5 horsepower.

For more information about Pumptec please visit our website and be sure to stay tuned for next week when we will continue to explore the Pumptec family of products.

Drought Insurance

Even with reliable brands and installation, some conditions are simply out of our control. For instance, half of the U.S. is currently experiencing a drought and has been for some time. During drought conditions, water levels in a well may drop below pump intake, causing an underload situation. With the lack of snow during the past winter and little rain during the spring and summer, wells could experience this drop either temporarily or long term.

Without significant rainfall to recharge aquifers, many private well systems are susceptible to the adverse impact of dry well conditions. If a well goes dry, the underload condition it causes can destroy the pump and/or motor.

Monitoring and diagnosing load issues can save a pump from damage and potential system failure caused by drought. Investing in a protection device before trouble hits can save a lot of time and money for you and your customer in the long run by shutting down the system to prevent damage when a dry well occurs.

Pumptec, for example monitors motor load and power line conditions to provide protection specifically against dry well/underload, as well as for waterlogged tanks and abnormal voltage. Upon detecting a fault, it interrupts power to the motor to give the well a chance to recover.

Franklin Electric wants to help make guarding systems from dry well conditions as easy as possible and Pumptec products are an ideal way to ensure a long and reliable pump life. During a lack of precipitation like we are currently experiencing, wells are more prone to going dry, due to either a drop in the water table or the fact that the well is getting used more. Sometimes the best investment isn’t the product itself, but what you do to protect it. We encourage you to protect your investment and make sure that once you put a pump downhole, you won’t have to see it again.

For more information about Pumptec, please visit our website, or get more information on how to protect a submersible water system from adversity, contact our Hotline at 800.348.2420 or hotline@fele.com.

 

Column-by-Column: Locked Rotor Amps and KVA

In our column-by-column review of single-phase motor specifications, we are finally at the last two columns on page 13 of the Franklin Electric AIM Manual. These two columns are Locked Rotor Amps and KVA Code.

Locked Rotor Amps, sometimes abbreviated LRA, is exactly what the name implies. If the rotor is locked and can’t move while electrical power is applied, the motor will draw this many amps. Locked Rotor Amps are much higher than running amps, generally around five times max running amps. For example, maximum load for a 1.5 hp, 2-wire motor are 13.1 amps. Locked Rotor Amps for this same motor are 66.2 amps.

An example of when the motor draws Locked Rotor Amps is in the case of a bound pump. In this scenario, the motor’s overloads will trip and take the motor offline in a few seconds to protect the motor.

However, another, much more common instance where the motor draws Locked Rotor Amps is at start up. That is, every time a motor is started, it pulls Locked Rotor Amps for a split second. The reason is that at the moment electrical power is applied, the rotor hasn’t started to rotate yet. So, for that instant, the motor thinks the rotor is locked. Once the motor starts to turn, amperage falls to something between full load and maximum amps. Once again, this happens very quickly, in a few tenths of a second.

Knowing the value of Locked Rotor Amps can be important in some installations, especially in terms making sure we’ve got the appropriate electrical service. For example, many older homes still have 50 amp service. So a 4-inch, 2-wire, 115 volt, ½ hp motor that pulls 64.4 amps at start up could potentially fail to start. There simply isn’t enough electrical current available to get the motor started. The equivalent 230 V motor in this case would be a much better option.

Locked Rotor Amps is also an important aspect of sizing reduced voltage starters (RVS). Reduced voltage starting is one type of soft starting, and these devices “ramp up” the voltage versus applying the full voltage all at once. This greatly reduces the Locked Rotor Amps at start-up.

Reduced voltage starters are rarely used with the single-phase motors listed here. However, if they were, this is where KVA Code comes in, and is used to specify the size of reduced voltage starters. Since reduced voltage starters are much more common and important with higher horsepower, 3-phase motors, we’ll save explaining where the KVA Code comes from when we discuss 3-phase motor specifications.

That wraps up the eighteen columns on page 13 of the AIM Manual. Next week, we’ll jump over to page 14 and start covering fuse and circuit breaker sizing.

For more help in the field concerning troubleshooting and installation, call our Technical Service Hotline at 800.348.2420 or email at hotline@fele.com.

Column-by-Column: Efficiency %

As we return to page 13 of the AIM Manual this week, this week’s post will focus on the column labeled Efficiency %.

Simply put, electric motors take electrical energy and convert it into mechanical energy. That is, we put electricity into the motor and out comes the rotation of a shaft that powers a pump. However, it’s not a “one-for-one” conversion; we don’t get the same amount of energy out of the motor that we put into it. The energy that is lost in the conversion process gets turned into heat. This happens not just with motors, but with all devices that convert energy from one form to another. Perhaps the most obvious everyday example is a light bulb. Only a small portion of the electricity that goes into a light bulb comes out as light energy. The rest becomes heat, as anyone who has touched a lit bulb knows.

This ratio between the amount of energy that we get out of something versus what we put into it is called efficiency. It’s generally stated as a percentage, but it can also be stated as a decimal.

The efficiencies of Franklin Electric’s single-phase submersible motors are listed on page 13 of the AIM Manual. Like several of the other columns on page 13, there’s a column for full load (FL) and one for maximum load, also called service factor load (SF). [For an explanation of service factor, see the Franklin AID post on Full Load Amps and Max Amps.] Since the motor operates at or near service factor most of the time, we’ll limit our focus to efficiency at service factor, or the SF column in the table above.

Using the 1 hp, 3-wire motor as an example, the table shows that the motor is 65% efficient. Once again, this simply means that 65% of the electrical energy that goes into the motor is available to turn the pump.

We can even calculate this ourselves as follows:

This is a 1 hp motor, but to keep the units consistent, we’ll use the equivalent value in kilowatts, in this case 0.75. We’ll also convert this to watts by multiplying by 1000 (kilo=1000). So, mechanically, this is a 750 watt motor. Since there’s a service factor involved of 1.4, this motor is actually a 1050 watt motor (750 x 1.4 =1050).

Now we know what we get out of the motor in terms of mechanical energy, but how much do we put into it in terms of electricity? That is found in the Maximum Load column under watts. That value is 1600 watts. So, we put 1600 watts of electricity into the motor and get 1050 watts out. That means the efficiency is:

1050 watts / 1600 watts = .65, or 65%

(output     /      input      =  efficiency)

This matches the 65% listed in the efficiency column.

Keep in mind that so far, we’ve just covered motor efficiency. The pump’s not going to be 100% efficient either, but we’ll cover that in another post.

In actual practice, the efficiency of smaller single-phase motors is generally not too critical. Because it actually costs so little to run a residential single-phase motor [refer to the Franklin in the Field post The Deal of a Lifetime], efficiency gains may only result in pennies of savings per day. Efficiency becomes more important, however, in applications with greater power consumption.

Next week we’ll move on to power factor in our attempt to make the numbers make sense, column-by-column.

Column-by-Column: Winding Resistance in Ohms

When we left Single-Phase Motor Specifications on page 13 of Franklin Electric’s Application, Installation, and Maintenance (AIM) Manual at the last post, we were ready for the column titled Winding Resistance in Ohms.

Single-phase motors have two windings, a start winding and a run winding. Technically, when the motor is a capacitor start/capacitor run type, these are called the auxiliary winding and the main winding respectively. However, we’ll just use the terminology of start and run windings to keep things simple.

Measuring winding resistance is a power-off check. Power must be disconnected and locked out.

Starting with 2-wire motors, winding resistance is measured between the two black motor leads. This can be done at the motor, at the well head, or even at the pressure switch. Referencing Table 13, the first thing noticed is the single row of values listed for 2-wire motors. For example, the ½ hp, 230 V 2-wire motor lists the winding resistance as 4.2 to 5.2 Ohms. This is the resistance of the run winding. But wait, where’s the value for the start winding? The answer is that because these are 2-wire motors, we don’t have access to the start winding. It’s there, but since this is a 2-wire motor, we can only measure the winding resistance between the two black leads; only one reading can be taken.

Notice that a range of values is provided, not exact numbers. And in reality, if you get something close to these numbers, the winding resistance is probably good.

In the case of 3-wire motors, winding resistance is measured for both the start and run windings. The main winding resistance is measured between the black and yellow leads. The yellow lead is the common here, and the start winding resistance is measured between the yellow and red lead. There’s no need to memorize this, since it’s in Footnote 1 at the bottom of the page.

Using a ½ hp, 230 V 3-wire motor as an example this time, we see that the main winding resistance is 4.2 to 5.2 ohms (same as the 2-wire motor). The start winding resistance is 16.7 to 20.5 ohms.

Winding resistance for 3-wire motors can be measured at the motor itself if it’s out of the well, at the well head, or at the control box.

Regardless of 2-wire or 3-wire, what does winding resistance tell us? When troubleshooting and measuring winding resistance, we’ll generally get one of three readings: zero, infinity, or a value close to what’s listed in the table. If the reading is zero, which indicates the winding is shorted. If the reading is infinity, which indicates the winding is open. In either case, the motor will need to be replaced. If the measurements are being taken at the well head we’ll also want to check the drop cable.

Winding resistance is one of two electrical checks, insulation resistance being the other, that tell us the electrical condition of the motor. If both the insulation resistance and the winding resistance are good, our motor is good from an electrical standpoint. It tells us that in terms of troubleshooting to look other places. By the way, we’ll cover insulation resistance in another post.

Column-by-Column: Full Load Amps and Max Amps

In the last post we explained service factor: that electric motors aren’t necessarily what is on the nameplate in terms of horsepower, they’re actually more. This difference is service factor. Read more about service factor in the post Column-by-Column: Motor Model and Rating.

Service Factor comes into play in the four columns in table 13 of the AIM Manual labeled Full Load and Maximum Load. These columns list current draw in amps and power consumption in watts.

Let’s begin with amps. Once again, notice there are two sets of columns: Full Load and Maximum Load. Full Load is the expected performance of the motor at the rated or nameplate hp. For example, if a 1/2 hp motor were delivering exactly 1/2 hp of power to the pump, it would be operating at Full Load amps. Maximum Load is what the motor would be delivering when service factor is included. As a result, Maximum Load is often also referred to as service factor amps or max amps.

Taking the 1/2 hp, 230 V example, when delivering 1/2 hp to the pump it draws 5.0 amps. However, if that same motor operates at its service factor of 0.8 hp (1/2 x 1.6) it draws 6.0 amps. In most installations, motors operate near the Maximum Load. Also note that these values assume the voltage at the motor is the nameplate voltage, in this case 230 V. If the voltage at the motor differs from this, the amperage will be slightly different.

The usefulness in having these numbers is that by measuring the current with an ammeter, we can determine how hard the motor is working. The more water we’re moving, the more electricity (current) the motor will need. For example, if we measure the current draw of the motor and it’s less than the Full Load value, that tells us the motor isn’t working very hard. Meaning, we’re pumping on the left side of the curve, we have a loose impeller, or possibly a pump “gulping” water.

If a motor’s amperage is measured and it’s over Maximum Load (service factor amps), it indicates that the motor is working too hard. This could be an indication of a binding pump or a case where we’re pumping on the right side of the pump curve.

Note: 2-wire motors only have a single row of figures. However, the 3-wire motors have 3 rows of figures representing the yellow, black, and red leads of a 3-wire motor. This points out an important difference between 3-wire motors without and with run capacitors. In the models without run capacitors, the red lead shows zero. This is because the start winding in these motors is only used for starting the motor. It comes out of the circuit as soon as the motor comes up to speed.

However, the remaining 3-wire motors with run capacitors all list current in the red lead. This is because in these motors, the start winding stays in the circuit after the motor has started. So, no run capacitor in the control box means zero current in the red lead. A run capacitor means there should be current in the red lead.

Power in electrical watts is listed next to amps and the same rules from above hold true here. The difference is, from a troubleshooting standpoint, we generally don’t have a way to measure power in the field directly. But, where those numbers are required is when calculating the cost to operate a submersible pump. For an explanation of how to do just that, see the Franklin in the Field post: http://franklininthefield.com/2011/04/26/the-deal-of-a-lifetime/

Next week, we will take a look at the column headed Winding Resistance In OHMS. We’ll see that it contains some especially valuable troubleshooting information.