MOST COMMONLY ASKED QUESTIONS ABOUT
S.T.E.M.S.
Saving Through Energy Management Systems

Band pass filter
Q. What does the band pass filter do?
A. The band pass filter blocks power spikes, surges and voltage transients significantly above or below the 60-cycle signal frequency. It blocks harmonic distortion to improve the flow of electricity to the inductive load. This causes the motor to run smoother, quieter and with lower resistance. This reduces motor frame temperature.

Q. Based on the components in the STEMS unit, what and how does each component perform its duties?
A. TVSS components act to remove transient voltages and filter capacitors act to improve Total Harmonic Disturbances, thus further conditioning the AC waveform. This has an effect of helping improve service life of equipment. The effect on motors is that (motors are moveable transformers), they are affected by the rise in current and frequency and generate a variance in the 60Hz waveform. The cumulative effect imposed upon contacts, coils, and semi-conductors by numerous disruptive surges, including harmonics, causes efficiency losses on the motors, which in turn will substantially increase power consumption as the motor compensates to meet demand. As pitting and corrosion occur, there is a rise in the operational temperature of the motor, which increases kilowatt usage and maintenance costs, as well as reduces the life expectancy of the motors and ballast.
MOV (metal oxide varistor), provides a perfect ground, removing high voltage and switching transient voltages.

Power factor correction

Q. What, if any, are the benefits to correcting power factor from .94 to .99?
A. Power factor correction extends overall service life to equipment. It also places demand factors within more favorable rate limits for monthly billing.

Q. What does the U.S. Department of Energy have to say about Power Factor reduction?
A. See U.S. Department of Energy fact sheet, attached.

Q. If the STEMS unit is connected to a panel with equipment having three different power factor ratings, will STEMS unit try to correct the worst power factor resulting in over correcting the best?
A. STEMS will enhance an average PF correction to any panel that has more than one PF source because the distribution network supplying different motors has an average power factor reading at any given point. STEMS will not over correct or cause harm to any of the motor loads, regardless of how many are running at different times, provided units are properly sized to the application. Over-correcting can occur only if too large a unit or too many units are used on a specific application.

STEMS Performance
Q. How do I forecast STEMS performance?
A. To forecast STEMS performance, you must find out the inductive load amp draw. STEMS Energy Management guarantees a 5% reduction in KWH usage on the treated inductive load.

Q. How do I do that?
A. Horse power x ¾ gives a rough estimate of inductive load, but prior to quoting a job, you must determine the actual amp load at the circuit breaker panel. You must test every amp leg every time.

Q. How is this reduction accomplished?
A. We reduce the amp draw, improve the power factor and reduce KVAR.

Wiring STEMS
Q. How does STEMS attach?
A. STEMS has three hot wires (yellow, brown orange), one neutral wire (white) and a ground wire (green). You attach each hot wire to one phase of the load and the neutral and the ground wires to a ground/neutral bar.

Q. Does the STEMS unit need its own breaker?
A. Ideally, yes. If that is not possible, use an NEC certified Wye to connect to a breaker already in use.

Q. If the STEMS unit is connected properly and is producing good results, what happens when the load begins to vary from the original load?
A. Should a load change, the STEMS unit will also change with the percent of overall savings decreasing as total load increase.

Q. Are there different STEMS models for different wiring systems?
A. No. The same STEMS three phase unit will work on delta or wye systems.

Q. Why are the “hot leads” different colors if it does not make any difference which phase they are connected too? Other brands use a specific color to connect to any “high leg”.
A. STEMS follows NEC Color Code Schemes brown, orange, yellow. High leg systems are not affected, because internal component values exceed that of the “high leg” voltage settings. Each unit is approved to hook up to supply sources @ 600VAC.

Best applications
Q. What are the best applications for STEMS and what should we stay away from?
A. Best applications are inductive motors for pumps and fans. Use smaller units on fluorescent lighting panels, the inductive load requirements are considerably less than those required on motor loads, even though the current maybe high.

Sizing
Q. How do I determine the correct size STEMS for a particular application?
A. The correct size STEMS for a particular application is determined by the amp draw per leg.
The following chart provides STEMS sizing parameters.

Q. Do I order the STEMS with special features such as KVAR, power factor, etc.?
A. No. STEMS work on 50/60 Hz, and 240VAC or 208-600 VAC.

Variable Frequency Drives
Q. How are STEMS installed in conjunction with variable frequency drives or soft starts?
A. STEMS must be installed before (up stream) of such equipment so that we do not interfere with their frequency. STEMS are always installed in parallel not in series because the voltage does not flow through the STEMS.

Q. What effect does STEMS have on motors with a variable frequency or variable speed drives?
A. STEMS improves the quality of the power supplied to a VFD or VSD. STEMS will make these drives last longer. STEMS must be installed upstream of the VFD or VSD, or it will have adverse effect on the
drive output, as the frequency changes on the output are significantly lower than the STEMS
bandpass range. In addition, the savings will be less than on motors without these drives.
We still make our 5% savings, but it is on a smaller load, with less wasted power, due to the
VFD or VSD.

Q. What effect does STEMS have on soft starts?
A. STEMS improves the quality of the power supplied to this device. STEMS will help this equipment to last longer. STEMS must be installed upstream of the soft start. Failure to do so will void the STEMS warranty and may damage the soft start.

Other Questions:

Q. What is STEMS warranty?
A. STEMS provides a three year pro-rated warranty against product failure. The first twelve months, provides free replacement, the next twelve months is 25% of the original cost and the final twelve months is 50% of the original cost.

Q. How does the 12 month money back guarantee work?
A. STEMS Energy Management guarantees a 5% reduction in KWH usage, assuming a constant load. If after a complete review of the facts, it is determined that the STEMS unit has not performed as stated, then the dealer will be responsible to refund the purchase price to the customer and return the used unit to STEMS ELECTRONICS, L.L.C. for a new replacement to go back in the dealer inventory.

Q. Does STEMS have a dealer information sharing program?
Active STEMS dealers share test results, to help each other introduce the product to potential customers. As you develop your own test results, you will become more confident in telling your own stories and have test results you can share as well.

Q. What is the life expectancy of STEMS?
A. The STEMS should last up to ten years with the original components. With our new design we are using higher quality components, so we really don’t know how much longer STEMS will last.

Q. How long would it take to get an order delivered to US cities?
A. Your order should ship in ten days.

Q. Are there any negatives to installing a STEMS unit on a residence?
STEMS will help residential applications, providing protection to expensive electronics and
providing energy savings.

Business Week Magazine (April9, 1991) “Electrical power pollution is costing businesses $26 Billion a year in damage and prevention.

Electronic microprocessor equipment requires clean power. This type of equipment needs undistorted voltage to function properly, and is particularly sensitive to voltage transient spikes and flat toppings of the 60Hz waveform.

In the past 10 years the processing speed, the volume of data that is transmitted, and the amount of data stored on computers has increased greatly. As the processing speeds of computers are increasing, the machines become more sensitive to voltage distortions.