| Torque Monitoring System |
| Q. | Why use a Torque Monitoring System? |
| A. | Maximum
Turbomachinery efficiency is very critical in today’s market due to rising
fuel costs and greater demand on emission controls. To get maximum
Turbomachinery efficiency, one has to measure the power output (continuous
on-line torque measurement of critical equipment), identify machine train
performance deterioration, and improve overhaul schedules so equipment can run
with its highest efficiency. When specifying a torquemeter, it is important to
recognize that a torquemeter is an integral part of a high performance coupling
and should be considered as a coupling-torquemeter system. Kop-Flex offers a monopole sensor type torque monitoring system called Powerlign or Powerwheel. Kop-Flex is the only company that designs and builds a coupling-torquemeter system. There are other vendors who offer a sensor type torque monitoring system. |
| Q. | What are different methods of measuring or monitoring torque output? |
| A. | There
are primarily two methods of measuring torque – strain gage or monopole sensor
type. Strain gage is relatively inexpensive, however has lower accuracy and
limited reliability, and is unstable over a long period of time due to
deterioration of strain gage and methods of affixing strain gage to coupling. The monopole sensor type is typically accurate within +1%, is highly reliable, has proven stability in the field over a long period of time, and is easy to maintain. However, its initial purchase price is more expensive than strain gage methods. |
|
Q. |
How does the monopole sensor type torque monitoring system (Powerlign or Powerwheel) work? |
| A. | The
principal behind the Powerlign (and Powerwheel) system is to measure the torque
deflection of the coupling spacer via sensors. The coupling spacer integrates
two sets of intermeshed pick up (gear) teeth, each attached to the ends of the
spacer. Two sensors are located over the pick up teeth, at 180 degrees to each other, near the rotating coupling. The sensors are mounted on the guards and hence do not rotate with the coupling. Only the coupling and pick up teeth rotate. As each set of teeth passes the sensor, a waveform is created. Torsional windup of the spacer, due to torque from driving equipment, causes the displacement in pick up teeth spacing. This spacing displacement changes the waveform. The sensor sends this signal to the display unit, where it is processed to provide torque and speed data. The display unit shows power (HP or kW) based on torque and speed and also displays the coupling temperature. The internal circuits to automatically compensate for temperature- associated changes continuously use the temperature information. |
| Q. | When do you select a Powerwheel over a Powerlign? |
| A. | Powerlign,
designed with a special spacer, is used in a typical high speed (performance)
torque measurement system, whereas the Powerwheel, a drop in “wheel” design,
is used with lightweight reduced moment design couplings on short shaft
separation (short distance between shaft ends) applications. Powerwheel can be
retrofitted in most existing gear, disc or diaphragm couplings supplied by most
coupling vendors.
Typical Powerwheel applications: ·
Low Torque ·
Higher Speeds ·
Very Short Shaft Separation ·
Very Long Shaft Separation ·
Sensitive/Critical trains Typical Powerlign applications: ·
High Torque ·
Low to Medium Speeds ·
Standard Shaft Separation Ranges ·
Less Sensitive Trains ·
Most Economical |
| Q. | Can the Powerlign System be installed with an existing coupling? |
| A. | Yes, for most applications the new spacer can be inserted without
disturbing the existing flex half couplings. |
| Q. | Is the Powerlign factory calibrated? Can it be field calibrated? How susceptible to damage is calibration? |
| A. | Yes,
the Powerlign is factory calibrated. There
is no need to field calibrate. The
Display Unit automatically checks and corrects itself (every 24 hours) for any
electronic drift. All electronic processing takes place within the Display unit
(usually mounted in the control), so there is no processing required in the
coupling environment. The Powerlign
teeth are shipped with a protective wrap, which is left on until the unit is
installed. |
| Q. | What are the sensors mounted on? |
| A. | They’re
mounted on the existing coupling guards by welding a boss plate to the guards.
The probes are inserted into the boss plates, and the gap is set with a
depth micrometer or feeler gages. The
orientations of the boss plates are usually put in at 45° to avoid any conflicts with drainpipes, vents, etc. |
| Q. | If “analog output” option is not chosen, what is output signal? |
| A. | The front of the display unit has an LED to display the output to the
user. The back of the display has a
port for standard analog outputs as well as an RS232 port for digital data
acquisition. |
| Q. | Typically, how long does it take to install a Powerlign? Do we need a service technician? |
| A. | Typically
it takes about a half shift longer than a plain non-instrumented coupling. A
field service technician is not needed. Installation
instructions are supplied ahead of time. Field
technicians are available upon request. |
| Q. | What is a zener barrier? |
| A. | It’s a special diode that is used for many electrical devices that operate in Hazardous Location Classifications. Powerlign sensors are certified as explosion proof for such applications. A zener barrier will be needed if the instrumentation is to be certified for Intrinsically Safe operation for use in Hazardous locations. This will be in addition to the explosion proof certification. |