WORKING WITH UNBALANCED POWER �FOR PUMP MOTORS

PHIL LUTHER

MIDWEST HYDRO DRILLING

SYMPTOMS OF UNBALANCED POWER

4 AREAS

SYSTEM REQUIREMENTS

A. IS THE INCOMING POWER AND TRANSFORMERS SIZED CORRECTLY?

1. TOTAL AMPERAGE LOAD MUST BE CALCULATED FOR THE TRANSFORMERS.

2. ADD IN THE SINGLE-PHASE LOADING FOR LIGHTS, HEATERS, AND CONTROLS.

3. OBSERVE TRANSFORMER SIZES OR SIDE OF GROUND TRANSFORMERS ON POWER POLES.

4. CAN STARTING LOAD BE HANDLED BY INCOMING POWER?

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SYSTEM REQUIREMENTS

B. IS THE MOTOR SIZED CORRECTLY FOR THE PUMP END?

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C. IS THE STARTER SIZED FOR THE MOTOR IN THE PANEL?

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D. DO YOU HAVE QUICK TRIP HEATER OR OTHER MOTOR PROTECTION?

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E. IS THE MOTOR CLASS SET CORRECTLY IN THE STARTER PARAMETERS? CLASS 10

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SYSTEM REQUIREMENTS

F. MOTOR PROTECTION, OVERVOLTAGE, UNDERVOLTAGE, SHORT CYCLING, LOSS OF PHASE, OVERHEAT.

1. USE A MOTOR SAVER DEVICE, FRANKLIN SUB MONITOR, GRUNDFOS MP204 OR SOMETHING SIMILAR.

2. THESE UNITS WILL RECORD AND SHOW UNBALANCED POWER SO YOU CAN IMPLEMENT CHANGES.

7. IS THE CABLE SIZED CORRECTLY FOR THE MOTOR?

1. CHECK THE DEPTH RATINGS AND CABLE BEING RATED FOR SUBMERSIBLE MOTOR POWER CABLE.

PRE-INSTALLATION

1. NOTIFY YOUR POWER COMPANY ON THE MOTOR DATA

1. MOTOR SIZE OR HORSEPOWER, 3-PH. 460 VOLTS OR 230 VOLTS.

2. FULL LOAD AMPS; 30 HP 460V IS 39.5 AMPS AND

30 HP 230V IS 79 AMPS= 40-AMP DIFFERENCE

3. FRANKLIN AND HITACHI MOTORS HAVE SIMILAR AMPS AND THE GRUNDFOS MOTOR HAS HIGHER AMPS.

PRE-INSTALLATION

B. MAKE SURE THE TRANSFORMERS AND KVA CODE ARE

LARGE ENOUGH TO RUN THE LOAD.

SEE THE TRANSFORMER CAPACITY CHART

TRANSFORMER CAPACITY CHART

PRE-INSTALLATION

C. IS THE INCOMING POWER A TRUE 3-PHASE, OPEN DELTA OR WYE SETUP? YOU CAN TELL BY LOOKING TO SEE IF YOU HAVE TWO OR THREE TRANSFORMERS.

D. DO YOU HAVE TOO MUCH SINGLE-PHASE LOADING ON THE SYSTEM?

START UP AND OPERATIONS

1. CHECK THE LINE VOLTAGE BEFORE STARTUP TO MAKE SURE VOLTAGE IS AT OR ABOVE REQUIREMENTS.

1. 480 VOLTS FOR 460V MOTOR

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START UP AND OPERATIONS

B. PERCENT VOLTAGE UNBALANCE IS DEFINED BY THE NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (NEMA):

100 TIMES THE ABSOLUTE VALUE OF THE MAXIMUM DEVIATION OF THE LINE VOLTAGE FROM THE AVERAGE VOLTAGE ON A THREE-PHASE SYSTEM, DIVIDED BY THE AVERAGE VOLTAGE.

FOR EXAMPLE, IF THE INCOMING POWER MEASURED LINE VOLTAGES OF 480, 483, 476= 480 VOLTS AVERAGE.

IT IS RECOMMENDED THAT INCOMING POWER VOLTAGE AT THE MOTOR TERMINAL DOES NOT EXCEED 1%. FOR EXAMPLE, 485V (HIGH) AND 475 (LOW) AVERAGE (NEMA) WOULD BE UNBALANCED.

START UP AND OPERATIONS

3. UNBALANCES THAT EXCEED 1% REQUIRE DERATING OF THE MOTOR MAY VOID THE WARRANTY.
4. DERATE THE MOTOR IF THE UNBALANCE IS GREATER THAN 1-2%. AN EXAMPLE IS IF YOU HAVE A 100 HP LOAD AND MOTOR, AND THE POWER IS UNBALANCED BY 3%, THEN YOU GET LESS HP FROM THE MOTOR. THIS LEADS TO OVERHEATING AND MOTOR FAILURE. ON AVERAGE, THE DERATING IS DOUBLE THE UNBALANCED AMOUNT.
5. CHECK VOLTAGE AND AMPERAGE AT LEAST ONCE PER MONTH. MORE OFTEN IF A PROBLEM ARISES.
6. DO A PHASE TO PHASE ROTATION IF SOME UNBALANCE OCCURS.
7. TIGHTEN ELECTRICAL CONNECTIONS ONCE A YEAR.
8. KEEP RECORDS OF YOUR OPERATIONS, GPM, PRESSURE, AMPERAGE, AND VOLTAGE.
9. CHECK PUMPS BOTH SUMMER AND WINTER AND COMPARE RESULTS.
10. LISTEN TO YOUR PUMPING EQUIPMENT. A CHANGE IN NOISE LEVEL OR RUMBLE MAY INDICATE FUTURE TROUBLE.

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CAUSES OF VOLTAGE UNBALANCE INCLUDE:

• FAULTY OPERATION OF POWER FACTOR CORRECTION EQUIPMENT. (UTILITY SIDE)
• UNBALANCED OR UNSTABLE UTILITY SUPPLY FOR THE INCOMING POWER.
• UNBALANCED TRANSFORMER BANK SUPPLYING THREE-PHASE LOAD THAT IS TOO LARGE FOR THE TRANSFORMER BANK.
• UNEVENLY DISTRIBUTED SINGLE-PHASE LOADS ON THE SAME POWER SYSTEM. (LIGHTS, HEATERS, CONTROLS, CHLORINATION)
• UNIDENTIFIED SINGLE-PHASE TO GROUND FAULTS.

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CAUSES OF VOLTAGE UNBALANCE INCLUDE:

• AN OPEN CIRCUIT ON THE DISTRIBUTION SYSTEM PRIMARY.
• THE EFFICIENCY OF AN 1,800 RPM, 100-HORSEPOWER(HP) VHS MOTOR IS GIVEN AS A FUNCTION OF VOLTAGE UNBALANCE AND MOTOR LOAD. STARTING AT 94% & DROPPING AS UNBALANCE INCREASES.
• SUBMERSIBLE MOTORS ARE ABOUT 80% TO 84% EFFICIENT, SO AN UNBALANCED POWER HAS A GREAT IMPACT.
• THE GENERAL TREND OF EFFICIENCY REDUCTION WITH INCREASED VOLTAGE UNBALANCE IS OBSERVED FOR MOTORS AT ALL LOAD CONDITIONS.

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LONG TERM OPERATIONS�SUGGESTED ACTIONS:

1. REMEMBER THIS IS ALL ABOUT OPERATING MORE EFFICIENTLY AND SAVING MONEY.
2. MONITOR VOLTAGES AT MOTOR TERMINALS TO VERIFY THAT INCOMING VOLTAGE IS BELOW 1% UNBALANCED.
3. CONSIDER INSTALLING SENSORS THAT SEND ALARMS FOR UNACCEPTABLE VALUES OR RATES OF CHANGE.
4. CHECK YOUR ELECTRICAL SYSTEM SINGLE-LINE DIAGRAMS TO VERIFY THAT SINGLE-PHASE LOADS ARE UNIFORMLY DISTRIBUTED.
5. DO A PHASE TO PHASE ROTATION.
6. HAVE POWER COMPANY ADJUST INCOMING POWER.
7. CHANGE YOUR SUBMERSIBLE MOTOR TO THE NEW MAG MOTOR. THEY ARE ABOUT 90-92% EFFICIENT.

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SUGGESTED ACTIONS:

6. INSTALL A VFD DRIVE

A. VFD WILL READJUST POWER TO MOTOR. THIS MEANS ALL 3 PHASES WILL HAVE SAME VOLTAGES.

B. CHANGE THE HERTZ TO SLOW RPM OF MOTOR TO FINE TUNE YOUR PUMP TO BETTER MEET YOUR NEEDS.

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CREDITS

FRANKLIN ELECTRIC

US ENERGY DEPT.

NEMA

ABB

PHASE TECHNOLOGIES

GRUNDFOS PUMPS

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PHIL LUTHER

MIDWEST HYDRO DRILLING

636-629-2424

PHIL@MHDS.US