Xylem 19 001 251 R3 Floboy VFD Pumping System - Manual (Page 17)

13
START-UP AND ADJUSTMENTS
Floboy Pumping Systems are pre-tested in the
factory and all controls are adjusted for the
operating conditions specified. However, there are
certain checks that must be performed prior to
energizing the pump station in order to prevent the
possibility of component damage. These voltage
checks can be performed by a qualified, licensed
electrician.
The required checks, procedures and adjustments
are as follows:
POWER CHECK
DANGER
Electrical wiring poses the danger of
hazardous voltage. Contact with live
electrical connections can cause shock,
burns or even DEATH. All electrical
connections should be made by a qualified
and licensed electrician and then inspected
by local code compliance authorities.
Have a licensed electrician check incoming
voltage to make certain it is in the range specified
and its variance and imbalance are within
acceptable limits. The pump's motor, starter and
wiring are sized for a particular nominal voltage;
either 120, 208, 240 or 480 volts. Voltage is
checked with a calibrated volt meter. On a three-
phase system (power is supplied with three or four
wires) there will be three fuses in the main
disconnect panel, A, B and C. It is important that
your electrician or technician check the voltage
between each fuse pair, i.e. A to B, B to C and A
to C. These voltage readings should be analyzed
in accordance with the following formulas:
VOLTAGE VARIANCE
1. Average the three voltage readings
2. Subtract the nominal voltage from this average
3. Divide the difference by the nominal voltage to
arrive at a percent variance
4. The maximum acceptable level for voltage
variance is 5%
EXAMPLE:
Assume the actual voltage readings on a nominal
480 volt system are:
A-B = 485 volts, B-C = 492 volts, and A-C = 472
volts
The average voltage is (485+492+472)/3 = 483
volts
The percent voltage variance is (483-480)/480
=.00625 or.625%
VOLTAGE IMBALANCE
1. Average the three voltage readings
2. Find the reading which has the widest deviation
by subtracting the average from each reading
3. Choose the largest difference and divide it by
the average voltage to arrive at a percent
imbalance
4. The maximum acceptable level for voltage
imbalance is 2%
EXAMPLE:
Assume the voltage readings described above
are:
A-B = 485 volts, B-C = 492 volts, and A-C = 472
volts
The average voltage is (485+492+472)/3 = 483
volts
The largest difference is (A/B - Avg.) 485-483 = 2
volts
(B/C - Avg.) 492-483 = 9 volts
(A/C - Avg.) 483-472 = 11 volts
The percent voltage imbalance is: 11/483 =.0228
or 2.28%
In this particular example the voltage variance is
acceptable while the voltage imbalance is not. If
your calculations show either result to be beyond
the acceptable limits noted, you should contact
your power company and have the power
corrected. Failure to do so could result in motor
current imbalance and excessive heat which
reduces the motor's lifetime.
PUMP PRIMING
As noted earlier, priming the pump is the process
of filling the pump's volute case and suction piping
in order to facilitate the pump's ability to move