Monarch Instrument Nova-Strobe vbx - Manual (Page 13)

9
Alternate Knob Function (multiple by 2, 3, 4, 5, etc.)
The tuning knob functions differently when ALT. is displayed. The
current flash rate is used as an adder. The knob will add (counter
clockwise) or subtract (clockwise) that initial flash rate for each “click”
the knob is turned. This in effect allows the user to multiply the initial
flash rate by 2, 3, 4, 5, etc up to the maximum flash rate. This is very
helpful on fan blades. Using this feature, one can superimpose the
blades on top of each other and check for blade tracking, bent blades,
lead and lag tests, etc.
For example: A 3 bladed fan is spinning at 3600 RPM. The strobe is
flashing at 3600 FPM. Press the ALT FUNCTION button to display
ALT. Then turn the knob counter clockwise 2 clicks. The strobe will
now flash at 10,800 FPM (effectively 3600 times 3). The fans blades
will be all superimposed on each other. One can now see if the blades
are out of alignment, bent, etc. by viewing the blades from the front or
viewing from the side edge of the blades.
To select a flash rate from a Preset (memory) location:
1.
Press the ALT FUNCTION button and then the MEMORY button.
2. READ will be displayed.
3. Turn the tuning knob to cycle through the preset flash rates.
4. Once the desired flash rate is displayed, press the MEMORY
button to select it. Press any other button to cancel.
5.
DONE will be displayed.
To store the current flash rate in a Preset (memory) location:
1.
Press the ALT FUNCTION button and then the MEMORY button.
2. READ will be displayed.
3. Do NOT turn the knob and press the MEMORY button again.
4.
STORE will be displayed.
5. Turn the tuning knob to cycle through the memory locations.
20
This section outlines the preparations and use of the strobe light in order
to be assured the measurements you are making are correct.
NOTE: A data collector or vibration analyzer is not needed in order to
do phase analysis. You do need a method of powering the
vibration transducer, you can use a self-generating velocity
transducer to “drive” the strobe light, or you can set ANALZ
ANALZ ANALZ ANALZ ANALZ to
NO in the menu and the strobe will power the vibration
transducer (accelerometer).
General preparation for phase analysis is as follows:
1. It is important to use a magnetic mounting base on the vibration
transducer.
2. Use a transducer cable that is long enough to allow you to get some
distance away from the strobe light.
3. Mount the strobe on a tripod so it can be fixed in one location.
4. Connect the vibration transducer to the strobe light (using a power
source or a data collector).
5. Start all measurements with the vibration transducer mounted on a
bearing housing in the vertical direction. (This is a good habit to get
into). Aim the strobe light at the selected reference mark and turn it
on. Adjust the flash rate to running speed and then set it to the
LOCK mode. Using the Phase adjust, position the reference mark to
the 12:00 o’clock position.
NOTE: Do not move the strobe location between
measurements.
Checking for looseness:
1. Keeping the vibration transducer in the vertical direction, move the
vibration transducer from the foundation, to the base plate, to a foot,