PM Vibration Exciter Type 480
Contents
1. esee CHAPTER 3 SPES eee Introduction PM Vibration Exciter Type 4808 Designed for long trouble free operation Vibration Exciter Type 4808 is a high quali ty compact machine with a permanent magnetic field It has a force rating of 112 newton 251bf enabling relatively heavy loads to be excited to high g levels The 4808 will normally be driven by Power Amplifier Type 2719 rated at 180VA but can also be driven by any amplifier up to a maximum input current of 15 A RMS without assisted cooling The moving element is supported by a robust rectilinear guidance system consisting of grouped radial and transverse flexures in a unique construction The flexures are made from a bonded sandwich of spring steel and a damping elastomer providing a clean acceleration waveform with low cross motion and low distortion characteris tics 2 PM Vibration Exciter Type 4808 User Manual Chapter 1 Operation Cooling Vibration Exciter Type 4808 can be used in environments with ambient temperatures up to 40 C 104 F Its maximum drive current rating is 15 ARMS but with assisted cooling this can be raised to 25ARMS Without assisted cooling operation at 15ARMS will cause the vibration table to become hot but will not damage the exciter The most efficient method of cooling is to suck air into the exciter via the air filter vents at the top of the exciter body For this purpose a domestic vacuum cleaner can be used with its suct2. SIONS Diameter 215 mm 8 46 in Height 200 mm 7 87 in COMPLIANCE WITH STANDARDS C compliance with EMC Directive compliance with EMC Requirements of Australia and New Zealand Safety EMC Emission and Immunity According to relevant standards EN 61010 1 IEC61010 1 UL3111 1 EN 50081 1 2 IEC61000 6 1 2 3 4 EN 61326 1 CISPR22 Class B limits FCC Rules Part 15 EN 50082 1 2 EN 61326 1 Temperature According to IEC60068 2 1 amp IEC 60068 2 2 Operating temperature 5 to 40 C 41 to 104 F Storage temperature 25 to 70 C 13 to 158 F Humidity According to IEC 60068 2 3 Damp Heat 90 RH non condensing at 40 C 104 F Mechanical Non operating according to IEC 60068 2 6 IEC 60068 2 27 IEC 60068 2 29 14 PM Vibration Exciter Type 4808 User Manual Index A AQ 0649 erna 7 C Cannon plug rr 7 Compliance with Standards 13 Construction 9 Cooling areas en 3 D Dimensions rr 4 Drive cable rr 6 7 E Exciter mounting rr 4 F Force rating sister dee 11 Frequency response 10 J JP 0O308 main tne dt Ee RE 7 M Magnetic assembly 9 Mains hum rr 7 Maximum acceleration 12 Mounting ce 4 Mounting dimensions 4 Mounting tool 6 Moving element sees 10 O Operating characteristics 9 Operating limits 11 Ope
3. Technical Documentation PM Vibration Exciter Type 4808 User Manual Br el amp Kj r amp SE PM Vibration Exciter Type 4808 User Manual Br el amp Kj r BE 0194 13 June 2006 Safety Considerations This apparatus has been designed and tested in accordance with IEC 61010 1 and EN61010 1 Safety Requirements for Electrical Equipment for Measurement Con trol and Laboratory Use This manual contains information and warnings which must be followed to ensure safe operation and to retain the apparatus in safe condi tion Special note should be made of the following Safety Symbols The apparatus will be marked with this symbol when it is important that you refer to the associated warning statements given in the manual e Protective Earth Terminal Hazardous Voltage Explosion Hazard The equipment is not designed to be used in potentially explosive environments It should not be operated in the presence of flammable liquids or gases Warnings Switch off all power to equipment before connecting or disconnecting their dig ital interface Failure to do so could damage the equipment Whenever it is likely that the correct function or operating safety of the appara tus has been impaired it must be made inoperative and be secured against unintended operation Any adjustment maintenance and repair of the open apparatus under voltage must be avoided as far as possible and if unavoidable must be carri
4. displacement increases as frequency de creases Therefore at frequencies up to 40Hz the exciter must be held within its 12 7 mm 0 5 maximum displacement limit in order to avoid hitting the overtravel stops At frequencies from 40 to 150Hz the maximum acceleration available is determined by the velocity limit which depends on the voltage available from the power amplifi er used to drive the exciter Chapter 3 RATED FORCE 112N 25 bf sine peak with assisted air cooling 187 N 42 Ibf peak FREQUENCY RANGE 5Hz to 10kHz bare table AXIAL RESONANT FREQUENCY 10 kHz bare table MAXIMUM BARE TABLE ACCELERATION 700 m s 71 9 MAXIMUM DISPLACEMENT 12 7 mm 0 5in peak to peak MAXIMUM VELOCITY 1 4 m s 55 in s DYNAMIC WEIGHT OF MOVING ELEMENT 160 gram 0 35 Ib STATIC FLEXURE STIFFNESS 5 6 N mm 32 Ibf in MAXIMUM INPUT CURRENT 15A RMS with assisted air cooling 25 A RMS CURRENT TO FORCE RATIO Coils in parallel approximately 0 16 A F sine peak Coils in series approximately 0 08 A F sine peak STRAY MAGNETIC FIELD 20x 103 Tesla at table face 8x 103 Tesla at 12 7 mm 0 5 in above table face COIL IMPEDANCE Approximately 0 80 at 500 Hz with bare table and coils in parallel Specifications TABLE SIZE 62 5 mm 2 45 in diameter FASTENING THREAD 5 x 5 16 18 UNC for M5 and 10 32 UNF inserts 1 central insert plus 4 equi spaced on circle of 250 8 mm TOTAL WEIGHT 35kg 77 11b DIMEN
5. e correct fastening torque is approximately 0 35 kg m 301b in To prevent this from being exceeded we recommend that you use a torque wrench when screwing test objects or fixtures to the vibration table Mounting Tool QA 0061 is provided for fitting inserts This has a locating pin at the end of its screw blade which fits into the threaded hole of an insert and prevents the tool from slipping sideways while the inserts are being screwed into the vibra tion table When properly fitted the inserts should be approximately 1mm 0 04 below the top of the table Never bottom an insert in the fixing hole and always ensure that the insert and hole are clean To lock an insert in place apply a small drop of cement to its outer thread before screwing it in suitable thread locking cement is available under Br el amp Kj r part no QS0003 To unscrew a locked insert you can weaken the cement by using a soldering iron to heat the insert Test Fixtures Since the points at which a test object can be attached do not always match the arrangement of fixing holes in the vibration table it is often necessary to make a fixture for fastening the object To prevent plate resonances from influencing the vibration response of the test object the dimensions of the fixture should be as small as possible Stingers and Pushrods For vibration mode studies on panels or other large structures it is generally con venient to have a central driving point awa
6. ed out only by trained service personnel Do not dispose of electronic equipment as unsorted municipal waste t is your responsibility to contribute to a clean and healthy environment by using the appropriate local return and collection systems Hazardous substances in electronic equipment may have detrimental effects on the environment and human health The symbol shown to the left indicates that separate collection systems must be used for any discarded equipment marked with that symbol Waste electrical and electronic equipment may be returned to your local Br el amp Kjaer representative or to Br el amp Kjaer Headquarters for disposal Copyright O 1984 2003 Br el amp Kj r Sound amp Vibration Measurement A S All rights reserved No part of this publication may be reproduced or distributed in any form or by any means without prior written consent from Br el amp Kj r Sound amp Vibration Measurement A S Naerum Denmark Table of Contents INTRODUCTION PM Vibration Exciter Type 4808 sees CHAPTER 1 Operation PE ere REN Exciter Mounting rte die eren EN Mounting Vibration Test Objects CHAPTER 2 Operating Characteristics sesse ee EE RR RE ner Gea idet ede aS Frequency Response and Resonance rnnnnnnnnnvennnvennnnnnnnnnenvnvenrnrennnnenenn Force Rating and Other Operating Limits
7. genous field a special jig is used to centre the flange Outside the gap the field strength is less than 0 02 Tesla which will not harm sensitive equipment or wristwatches used near the exciter Moving Element The moving element is a thin hollow cylinder with a vibration table at one end and a moving coil at the other It is designed to provide the best possible coupling be tween the force generated by the drive coil and the test object on the vibration table For maximum bare table acceleration and a high resonance frequency it has been machined from a solid piece of lightweight aluminium The vibration table is lapped and hardened by a deep electro chemical process to provide a smooth dura ble coupling with test objects The drive coil mounted at the bottom of the moving element is made up of two parallel windings These are coupled to a 4 pin Speakon plug on the side of the exciter body When connected in parallel they have a nominal impedance of 0 80 The maximum drive current rating is 15 ARMS which can be extended to 25 ARMS with assisted air cooling Eight radial flexures support the moving element in the field gap of the magnet assembly These are placed in sets of four above and below the gap and are fas tened by four vertical flexures to the sides of the cast iron flange at the top of the assembly The flexures accurately align the moving element so that the drive coil is centred in the gap allowing it to move up and down with
8. ion hose connected to one of the hollow carrying handles on the side of the exciter Note Using a vacuum cleaner to blow air into the exciter is not recommended as it may pre heat the air To ensure an adequate flow of air around the vibration table s drive coil 1 Unscrew and remove one of the exciter s carrying handles 2 Fit the 14 standard tube thread insert provided into the hole in the exciter body 3 Attach the vacuum cleaner s suction hose 4 If suction causes the vibration table to sink more than 1 mm below its normal position shift the position of the hose to give larger openings in the slots on the outside of the insert 4 PM Vibration Exciter Type 4808 User Manual Exciter Mounting For the majority of vibration tests the easiest way to mount the exciter is to place it upright with its base resting directly on a solid support such as a workbench or concrete floor If a more secure mounting is required you can use diameter bolts to fix the exciter to the support via the four fixing holes in its base Fig 1 1 Mounting Type 4808 Exciter 1 2 inch Diameter Bolts x Vibration Vibration Absorbent Absorbent Pad Sk Cushion N 030060 If it is important to minimise the vibrations transmitted to the mounting surface use a soft resilient pad under the exciter s base Alternatively place the exciter on its side on a soft cushion This is convenient for exciting panels or frameworks ho
9. on Plug Br el amp Kjaer Part No JP0308 that has to be sol dered on The connections are shown in Fig 1 5 Drive Cable AQ 0649 Exciter Drive Power Amplifier Type 2712 Input Socket Output Socket accepts with one of the Neutrik 4 pin Speakon plugs replaced with JP 0308 Drive Signal Coil Start Cannon Plug JP 0308 Neutral Coil Finish 030067 8 PM Vibration Exciter Type 4808 User Manual Chapter 2 Operating Characteristics Construction Fig 2 1 A sectional view of Vibration Exciter Type Kada 4808 Flexure Coil Vibration Rubber Table Boot Vertical Flexure Cast Iron Flange Iron Radial Pole Piece Flexure Columax Epoxy gt 9 34 Permanent Resin gt Magnet 030063 Magnetic Assembly Type 4808 has a Columax alloy permanent magnet which is epoxy bonded to the base The thick metal base and cylindrical body of the exciter are machined from mild steel and form part of the magnetic path high purity cylindrical iron pole piece projects from the magnet into the hole at the centre of a cast iron flange This is fixed to the top of the exciter body and creates a 2 55 mm 0 1 field gap around PM Vibration Exciter Type 4808 User Manual the pole piece A magnetic field of approximately 1 Tesla 104 Gauss is produced in this gap To help ensure a uniform gap and homo
10. out twisting or rubbing against the sides of the gap Each flexure is a sandwich of spring steel plate bonded with rubber This helps damp the resonance modes of the suspension The maximum displacement limit of the moving element os 12 7 mm 0 5 peak to peak Rubber stops above and below the gap help protect the element from over travel The stops are designed to withstand an occasional high velocity impact and are for emergency use only If the flexures hit the stops a bumping sound will be heard warning you to reduce the drive level immediately Frequency Response and Resonance Fig 2 2 shows a plot of the frequency response of a Type 4808 The acceleration level is in g and ms and is plotted against frequency for a constant drive voltage The acceleration level increase with frequency to reach a damped peak at about 150 Hz This is the electro mechanical resonance a result of the back e m f induced in the moving coil damping the suspension resonance of the exciter The acceleration level then remains constant from 300Hz to 4 kHz after which it climbs steeply to a peak at about 12 kHz This peak is the major axial resonance of the moving element It can be seen that the exciter can be used at frequencies between 300 Hz and 4 kHz with CHAPTER 2 Operating Characteristics 11 out using a compressor loop to control the level of the drive signal However we recommend the general use of a compressor loop as resonances in the te
11. ration itd 3 P Power amplifier 1 6 7 P shrods unum ete As Ss 6 QA 0061 ER EE NE 6 Q5 0003 an aa 6 R Resonance sea Ee ed nahen 10 S Specifications 13 Standards EAS 13 Stingers teet ee nie 6 T Test fixtures seu 6 Test objects sees 4 Threaded inserts 5 Type 2712 nl ee gue 7 Type2718 usa 6 Type 2119 ie ee ees 1 6 V Vibration test objects iese sees ee ee ee 4 Y YS0810 mn SA Ress 5 EA OE a ns ak 5 16 PM Vibration Exciter Type 4808 User Manual HEADQUARTERS DK 2850 N rum Denmark Telephone 45 4580 0500 Fax 45 4580 1405 www bksv com info bksv com Australia 61 2 9889 8888 Austria 43 1 865 74 00 Brazil 55 11 5188 8161 Canada 1 514 695 8225 China 86 10 680 29906 Czech Republic 420 2 6702 1100 Finland 358 9 755 950 France 33 1 69 90 71 00 Germany 49 421 17 87 0 Hong Kong 852 2548 7486 Hungary 36 1 2158305 Ireland 353 1 807 4083 Italy 39 0257 68061 Japan 81 35715 1612 Republic of Korea 82 2 3473 0605 Netherlands 31 318 55 9290 Norway 47 66 77 11 55 Poland 48 22 816 7556 Portugal 351 21 4169 040 Singapore 65 377 4512 Slovak Republic 421 25 443 0701 Spain 34 91659 0820 Sweden 46 33 225 622 Switzerland 41 44 8807 035 Taiwan 886 2 2502 7255 United Kingdom 44 14 38 739 000 USA 1 800 332 2040 Local representatives and service organisation
12. rizon tally Mounting Vibration Test Objects Mounting Dimensions Fig 1 2 shows the outline and mounting dimensions of Type 4808 Each of the five holes in the vibration tables has an 5 16 18UNC tapped thread and is 8mm deep accepting one of the inserts provided CHAPTER 1 Operation 5 Fig 1 2 EUM Outline and mounting dimensions of 4808 62mm wo EN Oo ITI Q Ya BS Pipe Thread e o N 5 x 5 16 18 UNC o i oo R Y for M5 and 10 32 UNF inserts One central F insert plus four equi spaced on circle of 50 8mm dia Thread Inserts M5 YS 0810 10 32 UNF YS 0811 175 219 S 4 pin NEUTRIK Speakon 14 mm dia NL3MP 179 5 030062 To prevent damage to the exciter a test object should be mounted with its centre of gravity in line with the central fixing hole Avoid fastening test objects directly to the fixing holes use the threaded inserts provided Threaded Inserts Two types of threaded insert are provided for fixing vibration test objects e YS0810 converts the 5 16 18UNC thread of the vibration table s fixing holes to M5 e YS0811 converts the 5 16 18 UNC thread to 10 32 UNF 6 PM Vibration Exciter Type 4808 User Manual The inserts act as mechanical fuses which strip their inner thread before excessive force or fastening torque can strip the thread of the vibration table s fixing holes Th
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14. st object must be considered Fig 2 2 Typical frequency response of Type 4808 EE Has A Hier warum Ham Meet d imr ff ii Hin EE A E 1 rus Force Rating and Other Operating Limits The force F required to vibrate a mass m with an acceleration a is given by F ma By rearranging and including the effective mass of the exciter s moving element me we obtain F m m from which the maximum acceleration of the exciter with any payload can be calcu lated a Example Type 4808 has a moving element with effective mass m 0 16 kilogram Without assisted cooling the maximum force rating is 112N The maximum acceleration when loaded by a test object of mass m 0 5 kilogram is given by gud uu dic cum E 173g m m 0 5 0 16 12 PM Vibration Exciter Type 4808 User Manual Fig 2 3 Performance limits for sine operation of Type 4808 with and without assisted cooling JIM a TR gi Saw Table Aus m r P1 g Barm Tate GU man 50 Parka BE gramme MI IE m Acceso Pg Sie p in ibp Feisa 2120 gramme i4 85 Ini d po me ER ns anbud cred ing i J ie re EET TT se MP 100 Ki mW l 23 5 m 030065 The maximum acceleration with other loads can be determined from the load rating curves in Fig 2 3 Above 150Hz the limits are based solely on the available force However for a given acceleration level
15. y from the exciter For this purpose a stinger such as a nylon stinger from Stinger Kit WZ 0066 or a purpose built pushrod can be used to transfer the force from the fixing hole at the centre of the vibration table An example of the purpose built pushrod is shown in Fig 1 3 Fig 1 3 Typical pushrod for use with Type 4808 Hose Clamp Thin Aluminium Tube lt 10 32 UNF Slot 030061 Connection of Power Amplifier Drive Cable AQ 0649 is provided with the exciter for connection of a power amplifier to the vibration table drive coil Its plug connections are as shown in Fig 1 4 and it is suitable for direct connection to the Power Output socket of Power Amplifiers Types 2718 and 2719 CHAPTER 1 Operation 7 Fig 1 4 AQ 0649 Soldering side of Plug shown Drive Cable AQ 0649 connections viewed Brown from the outside Yellow Green 010113 2 If there is a mains hum when powering the exciter the power amplifier and exciter are probably grounded at more than one point To prevent this isolate the base of the exciter from ground or alternatively disconnect the Amplifier Chassis Exciter Body connection the yellow green coloured cord between the two 2 terminals in the AQ 0649 cable at one of the two plugs Note To connect with an old Br el amp Kj r Power Amplifier Type 2712 you must remove one of the Neutrik 4 pin Speakon plugs from Drive Cable AQ 0649 and re place it with 3 pin Cann
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