•
Broken or damaged shaft
•
Broken or damaged coupling
•
Jammed impeller
•
Bad bearings
•
Rapid cycling
The power draw at each of these conditions can be simulated in a plant test or estimated through calcu-
lations or interpolations from the pump performance curve. By defining these dangerous power fluctua-
tions, appropriate calibration of the power-monitoring unit prevents avoidable pump failures. This figure
shows a typical power evaluation recorded from a common centrifugal pump electric motor.
20
20
0
0
0
0
1
2
3
4
1.
The pump is in operation.
2.
The valve is closing.
3.
The valve is opening.
4.
There is no fluid being pumped.
Figure 37: Typical power evaluation
Contact your ITT representative for assistance and power analysis for your specific system. For further
details and evaluation of power monitoring units, a comprehensive power monitor user guide is available
from ITT.
Calibration tips
Use these tips to assist you when you select and calibrate power monitors:
•
Read your power monitor installation instructions and wiring diagram before you attempt to cali-
brate the unit.
•
Understand the recommended operating envelope of your pump provided by ITT.
•
Understand the requirements and limitations of your system.
•
Understand the full range of your operating duty, including power requirements at the rated mini-
mum and maximum flow conditions.
•
Identify potential failures that would be characteristic of your specific process and pump type.
•
Understand the power scope and torque scope of the selected electric motor.
•
When feasible, further define your operating range to run as close to best efficiency point (BEP) as
practical.
•
Select either a single trip unit or dual trip unit as practical for your specific system. A dual trip unit is
recommended for the 3296 EZMAG. Always use a low setting in order to protect against dry run. A
high setting detects if an upset condition has occurred. This results in bearing damage.
•
Set a low-power trip point at the required power draw when operation is at the recommended mini-
mum flow of the manufacturer or higher, but less that the normal operating point.
•
Set a high-power trip point at the required power draw when operation is at the recommended max-
imum flow of the manufacturer or lower, or at the flow rate that will prevent cavitation.
•
When using dual trip power monitors, select high and low trip points designed to protect your spe-
cific system within the recommended pump operating region that is defined by ITT. This method
creates boundaries for a safe pump operating envelope.
9.1 Condensed power monitor
Model 3296 EZMAG Installation, Operation, and Maintenance Manual
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