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5.0  USING THE STROBOSCOPE TO MEASURE RPM

The primary use for a stroboscope is to stop motion for diagnostic inspection 

purposes.  However  the  stroboscope  can  be  used  to  measure  speed  (in 

RPM/RPS). In order to do this several factors need to be considered. First, 

the object being measured should be visible for all 360° of rotation (e.g. 

The end of a shaft). Second, the object should have some unique part on 

it, like a bolt, keyway or imperfection to use as a reference point. If the 

object being viewed is perfectly symmetrical, then the user needs to mark 

the object with a piece of tape or paint in a single location to be used as a 

reference point.  

Look only at the reference point.

If the speed of rotation is within the range of the stroboscope, start at the 

highest flash rate and adjust the flash rate down. At some point you will 

stop the motion with only a single reference point of the object in view. 

Note that at a flash rate twice the actual speed of the image, you will see 

two  images  (reference  points).  As  you  approach  the  correct  speed,  you 

may see three, four or more images at harmonics of the actual speed. The 

first SINGLE image you see is the true speed. To confirm the true speed, 

note the reading and adjust the stroboscope to exactly half this reading, or 

just press the ÷2 button. You should again see a single image (which may 

be phase shifted with respect to the first image seen).

For example, when viewing a shaft with a single keyway you will see one 

stationary image of the keyway at the actual speed and at 1/2, 1/3, 1/4, 

etc, of the actual speed. You will see 2 images of the keyway at 2 times 

the actual speed, 3 keyway at 3 times, etc. 

The Flashes Per Minute (FPM) 

equals the shaft’s Revolutions Per Minute (RPM) at the highest flash rate 

that gives only one stationary image of the keyway.

Summary of Contents for Phaser-Strobe pbx

Page 1: ...on Manual Phaser Strobe pbx Portable Phase Shifting Stroboscope 15 Columbia Drive Amherst NH 03031 USA Phone 603 883 3390 Fax 603 886 3300 E mail support monarchinstrument com Website www monarchinstr...

Page 2: ...ce from moving machinery and do no touch the target 7 There are lethal voltages present inside this product Refer to the section on Lamp Replacement before attempting to open this product 8 Do not all...

Page 3: ...y Registration and Extended Warranty Coverage information is available online at www monarchinstrument com Monarch Instrument holds the following US trademarks and registrations all rights reserved il...

Page 4: ...erMode ExternalInputRequired 10 4 5 ExternalDelayModes PhaseShifting 10 4 6 PowerUpFeatures 11 5 0 USING THE STROBOSCOPE TO MEASURE RPM 12 6 0 LIMITATIONS OF REMOTE OPTICAL SENSORS 14 7 0 LAMP REPLACE...

Page 5: ...Additional information displayed include PHASE Indicates Phase Shift Delay Mode is active TIME Indicates Phase Shift Time Delay Mode is active AUTO Indicates Auto Phase Shifting Mode Virtual RPM is a...

Page 6: ...nd RPS External Phase or Time Delay Mode cycles display through RPM RPS Phase and Time Auto Mode cycles display through RPM RPS VRPM and VRPS ALT Function toggles Tach Mode flashing on off INPUT MEMOR...

Page 7: ...g the internal batteries the unit should be charged before use see section 8 2 Charging the Batteries The actual operating time of the stroboscope depends on the flash rate and duty cycle of operation...

Page 8: ...rs that are powered by the Phaser Strobe pbx e g Remote Optical Sensor ROS P the sensor must be plugged in before the stroboscope is turned on or the remote sensor may not be powered up The input jack...

Page 9: ...decimal places backlight on or off positive or negative edge for input and output signal and input blanking on or off To enter the MENU 1 Press the ALT FUNCTION button and then the MENU button 2 SETU...

Page 10: ...for the Phaser Strobe pbx These are Internal External Input External Phase Delay External Time Delay and Auto Virtual RPM All but the Internal Mode require an external input signal In the Internal Mod...

Page 11: ...ash rate below the minimum flash rate To multiply or divide the current flash rate by 2 In addition to the knob there are two buttons on the display panel marked x2 and 2 These enables the user to ins...

Page 12: ...played press the MEMORY button to select it Press any other button to cancel DONE will be displayed To select a current flash rate in a preset memory location 1 Press the ALT FUNCTION button and then...

Page 13: ...ashing Press the ALT FUNCTION button and then the TACH button The TACH icon will be displayed To start flashing again Press the ALT FUNCTION button and then the TACH button The TACH icon will go away...

Page 14: ...ress the ALT FUNCTION button and then the TACH button The TACH icon will go away 2 The unit will remain in the External Input Mode unless the INPUT button is pressed to change the mode 4 5 External De...

Page 15: ...IME or AUTO icon will go away 4 6 Power Up Features When the strobe is powered up it will remember the last settings Press and hold the x2 MENU button then turn on the strobe by depressing the trigger...

Page 16: ...wn At some point you will stop the motion with only a single reference point of the object in view Note that at a flash rate twice the actual speed of the image you will see two images reference point...

Page 17: ...g the speed until you reach a third SINGLE image at speed C For a two point calculation the actual speed is given by RPM AB A B For a three point calculation RPM 2XY X Y X Y 2 where X A B and Y B C If...

Page 18: ...milliseconds depending on the flash rate This limits the largest delay possible because the flash swamps the signal from the ROS and consequently it will not provide the pulse from the reflective mark...

Page 19: ...to remove the reflector Hold the lamp with a cloth between your forefinger and thumb and rock it back and forth gently while pulling out Do not attempt to rotate the lamp The lamp is socketed and wil...

Page 20: ...ns rotation see Figure 4 Push the tabs on the front rim outward and press the lens into place 7 2 Fuse Under normal operating conditions the fuse within the stroboscope should never blow Examples of a...

Page 21: ...3 5 cycles of charging and discharging for batteries to reach full capacity The enclosure contains control electronics to properly and safely charge the batteries Never remove the batteries from the e...

Page 22: ...charger will fast charge the batteries for about 4 5 hours and then trickle charge the batteries Allow the charger to charge the batteries until the display shows DONE for peak battery life performanc...

Page 23: ...t to a recycling center or returned to the factory The rest of the parts may now be disposed of 9 0 SPECIFICATIONS Flash Range 30 50 000 FPM Flashes Per Minute Flash Rate Accuracy 0 004 of setting or...

Page 24: ...t setting before power down is remembered and restored on the next power up 9 user settable flash rates Trigger Output Remote Sync 1 8 phone plug 40 sec positive negative pulse menu selectable 3 3VDC...

Page 25: ...stops flashing in the event of internal overheating Unit must then be power cycled Humidity Maximum relative humidity 80 for temperature up to 88 F 31 C decreasing linearly to 50 relative humidity at...

Page 26: ...drops and infiltration of contaminants 6280 034 C 4027 Set of mating 1 8 3 5 mm stereo phone plugs to provide TTL signal and sensor power 6280 037 CA 4044 6 6 ft 1 8 m Input Output cable 1 8 3 5 mm ma...

Page 27: ...ed Sensor with 8 ft 2 5 m cable for use without reflective target at 0 5 inch 12 mm gap for triggering strobe 6180 036 MT 190P Magnetic Trigger Sensor Amplifier with 8 ft 2 5 m cable for triggering st...

Page 28: ...nstrument is committed to excellence and quality in manufacturing sales and service The Professional s Choice Track It Data Loggers Panel Tachometers DataChart Paperless Recorders Speed Sensors Portab...

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