BRUEL & KJAER 4294 User manual

Technical
Documentation
HEADQUARTERS: Brüel&Kjær Sound & Vibration Measurement A/S · DK-2850 Nærum · Denmark
Telephone: [phone] · Fax: [phone] · www.bksv.com · [e-mail]
Local representatives and service organisations worldwide
Calibration Exciter
Types 4294 and 4294-002
English BE0739–15
User Manual
ËBE-0739---GÎ

BE0739–15 April 2014
Calibration Exciter
Types 4294 and 4294-002
User Manual
From serial no. 2863100

Copyright 1984 – 2014, Brüel&Kjær Sound & 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 Brüel&Kjær Sound & Vibration Measurement
A/S, Nærum, Denmark
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, Control and Laboratory
Use. This manual contains information and warnings which must be followed to ensure safe
operation and to retain the apparatus in safe condition. 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.
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 digital interface.
Failure to do so could damage the equipment.
• Whenever it is likely that the correct function or operating safety of the apparatus 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 carried out only by trained service
personnel.
• Do not dispose of electronic equipment or batteries as unsorted municipal waste
• It 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 or batteries 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 or batteries marked with that symbol
• Waste electrical and electronic equipment or batteries may be returned to your
local Brüel&Kjær representative or to Brüel & Kjær Headquarters for disposal

Contents
CHAPTER 1
Introduction......................................................................................................... 1
CHAPTER 2
Operation............................................................................................................. 3
2.1 Environment and Handling................................................................................... 3
2.2 Battery Installation and Replacement.................................................................. 3
2.3 Mounting a Transducer........................................................................................ 4
2.4 Basic System Calibration..................................................................................... 5
2.5 Transducer Sensitivity Check .............................................................................. 6
CHAPTER 3
Specifications..................................................................................................... 9
3.1 Compliance with Standards................................................................................. 9
3.2 Specifications..................................................................................................... 10
3.3 Dimensions........................................................................................................ 11
CHAPTER 4
Service and Repair........................................................................................... 13

1
Chapter 1
Introduction
USES
• Precise field calibration of vibration transducers
• Rapid calibration and checking of vibration transducer sensitivity
• Quick, easy field calibration of vibration measurement and recording systems
FEATURES
• Small, lightweight, and battery-driven
• Leather case for impact protection
• Designed for everyday use in harsh environments
• Acceleration, velocity and displacement calibration
• High-precision, crystal-controlled servo operating at 159.15 Hz (1000 rad s–1)
• Drop- and environment-tested according to IEC 60068
• Splash-proof according to IP 54 (IEC 60529)
Description
Type 4294 enables accurate adjustment of measuring instrumentation at a standard acceleration
level of 10 ms–2 (0 – 70 gram load). The reference signal can also be used for velocity and
displacement calibration at 10 mms–1 and 10 µm, respectively.
Type 4294-002 enables accurate adjustment of measuring instrumentation at a standard
acceleration level of 3.16 ms–2 (0 – 200 gram load). The reference signal can also be used for
velocity and displacement calibration at 3.16 mms–1 and 3.16 µm, respectively.
The calibrator contains an electromagnetic exciter driven by a crystal oscillator at a frequency
of 159.15 Hz (1000 rad s–1). A small accelerometer on the underside of the vibration table
provides servo feedback to maintain a constant, accurate vibration level independent of the
mass of the transducer under test (maximum 70 gram for Type 4294 and 200 gram for
Type 4294-002).

Calibration Exciter Types 4294 and 4294-002 – User Manual2
Fig.1.1
Calibration Exciter
Type 4294 in its leather
case
To prevent overload, power to the calibrator is automatically disconnected if a transducer mass
above 70 gram for Type 4294 or 200 gram for Type 4294-002 is mounted on the exciter’s
vibration table.
Use of the calibrator is straightforward. You can attach a transducer to the vibration table using
(see Fig.2.2):
• 10 – 32 UNF Steel Stud YQ-2962
• 10 g Mounting Disc DB-2996 (supplied) for transducers:
– with 3 mm threads
– fitted with Mounting Magnet UA-0642
– mounted with beeswax
Note:
Mounting using adhesive is not recommended.
To switch the calibrator on, press the small button on the side of its housing.
After system adjustment, turn the calibrator off by pressing the button again.
To prolong the battery life, the exciter automatically switches off after approximately
100 seconds.

3
Chapter 2
Operation
2.1 Environment and Handling
Calibration Exciter Type 4294 is designed for use in environments at temperatures within the
range –10 to +55°C (+14 to +131°F) and with relative humidity up to 90% RH (30°C (86°F),
non-condensing). Whenever possible, the exciter should be used in its leather case (see
Fig.1.1) to protect it from mechanical damage and contamination from grease or dirt.
2.2 Battery Installation and Replacement
For powering Type 4294, a long-life alkaline battery QB-0016 (IEC Type 6LR61) is
recommended. The battery fits into the battery holder, which is accessible after unscrewing the
base of the calibrator (see Fig.2.1). To prevent damage, take care not to cross the screw thread
on reassembly.
To maximise battery life, Type 4294 automatically switches off after approximately 100 s.
Using Battery QB-0016, approximately 200 calibrations, each of approximately 100 s, are
possible. After this, the operating period rapidly decreases, indicating that the battery needs to
be replaced. However, the exciter can be used until its battery is fully depleted without
influencing the accuracy of the reference level generated.
Fig.2.1 9 V battery installed in the calibrator

Calibration Exciter Types 4294 and 4294-002 – User Manual4
2.3 Mounting a Transducer
Types 4294 and 4294-002 are designed for use with Brüel & Kjær Accelerometers with
maximum weights of 70 and 200 grams, respectively. The accelerometers can be mounted with
“finger-tight” mounting torque (~0.3 Nm, max. 0.5 Nm) directly onto the vibration table using
a 10–32 UNF steel stud YQ-2962, or mounted with the aid of Mounting Disc DB-2996 for
transducers weighing less than 10 grams. Different mounting options are illustrated in Fig.2.2.
Caution:
If the specified torque is exceeded, be sure to apply a similar counter-torque to the armature in
order to protect the vibration table from damage
The mounting disc lets you attach accelerometers in several ways. Small transducers fitted with
3 mm threads can be attached using 3 mm Steel Stud YQ-2007. Alternatively, a Mounting
Magnet UA-0642 or Beeswax YJ-0216 can be used to attach transducers to the mounting disc.
Fig.2.2 Transducer mounting options
4294 or 4294-002
Calibration Exciter
Accelerometer
with Integral
10-32 UNF Stud
10-32 UNF
Threaded
Accelerometer
10-32 UNF
Threaded
Accelerometer
M3 Threaded
Accelerometer
Accelerometer
with Integral
M3 Stud
Accelerometer
without
Base Thread
¼-28 UNF
Threaded
Accelerometer
10-32 UNF
Mounting Thread
YQ-2962
10-32 UNF Stud
UA-0642
Mounting
Magnet
YQ-2007
M3 Stud
YJ-0216
Beeswax
UA-2062
¼-28 UNF to
10-32 UNF Stud
DB-2996 Mounting Disc
(3 mm tapping, 10-32 UNF thread)
+
Z
+
140090

CHAPTER 2
Operation 5
2.4 Basic System Calibration
The following procedure can be used for quick, accurate adjustment and calibration of
vibration measurement systems for a reference acceleration level of 10 ms–2 RMS/14.14 ms–2
peak for Type 4294 (3.16 ms–2 RMS/4.47 ms–2 peak for Type 4294-002). Calibration using
reference values of velocity or displacement is also possible, as mentioned in step 6).
1) Attach the system transducer to the vibration table (finger-tight is sufficient) of the
calibrator using either a 10–32 UNF Stud YQ-2962 of Mounting Disc DB-2996. See
section 2.3.
2) Connect the transducer to the vibration measurement system using a suitable low-noise
cable, for example, that supplied with the transducer. Where a preamplifier with adjustable
sensitivity conditioning is employed, the accelerometer sensitivity specified on the
calibration chart should be entered prior to setting the measuring range of the read-out
instrument.
3) Switch on the preamplifier and indicating instrument and select the acceleration mode and
the highest indicating range on the appropriate instruments.
4) Press the button on the side of the calibrator to vibrate the transducer. The transducer is
now subjected to a sinusoidal acceleration of 10 ms–2 RMS ±3% (4294-002: 3.16 ms–2
RMS ±3%) at a frequency of 159.15 Hz (that is, ω= 1000 rad s–1).
5) Switch the range controls of the preamplifier and/or indicating instrument to obtain an on-
scale meter indication without the overload lamps of the instruments lighting.
The indicating instrument should now indicate a reference acceleration level of 10 ms–2
RMS (4294-002: 3.16 ms–2 RMS). If not, adjust the sensitivity potentiometer of one of the
instruments until the correct reference level is indicated. Once correctly set, avoid further
adjustment of the sensitivity potentiometer, as the calibration will be lost.
Note: If an indicating instrument with peak indicating mode is employed, then it should be
adjusted to indicate a reference level of 14.14 ms–2 peak (4294-002: 4.47 ms–2 peak).
6) For velocity and displacement calibration of the vibration measurement system, the
preamplifier/measuring instrument should be equipped with integration networks. The
appropriate measurement mode should therefore be selected before switching the
calibrator on. The relevant calibration levels are as follows:
Velocity: 10 mms–1 RMS/14.14 mms–1 peak ±3%
(4294-002: 3.16 mms–2 RMS/4.47 mms–2 peak ±3%)
Displacement: 10 μm RMS/14.14 μm peak ±3%
(4294-002: 3.16 μs–2 RMS/4.47 μs–2 peak ±3%)
Fig.2.3
Example of calibration of a
vibration measurement
system
4294 or 4294-002
Calibration Exciter
2635
Charge Amplifier
Digital
Voltmeter
140096

Calibration Exciter Types 4294 and 4294-002 – User Manual6
2.5 Transducer Sensitivity Check
For determination of the actual sensitivity of transducers, calibrated preamplifier and
indicating instrumentation are required. Although not intended for absolute sensitivity
measurement, the following procedure provides an approximate sensitivity check, sufficient
for determining whether a transducer functions correctly and has not been damaged during
previous use.
1) Attach the system transducer to the vibration table (finger-tight is sufficient) of the
calibrator using either a 10–32 UNF Stud YQ-2962 of Mounting Disc DB-2996. See
section 2.3.
2) Connect the transducer to the vibration measurement system using a suitable low-noise
cable, for example, that supplied with the transducer. If a voltage preamplifier is
employed, it is important that the particular cable supplied with the transducer is used,
otherwise the voltage sensitivity of the transducer will be affected.
3) In the case of a vibration meter, RMS indication of acceleration and an appropriate
measurement range should be selected. If a conditioning preamplifier featuring direct dial-
in of charge or voltage sensitivity is employed, the relevant sensitivity specified on the
transducer’s calibration chart should be entered before setting the range of the calibrated
indicating instrumentation.
4) Switch on the preamplifier, indicating instrument and calibrator in that order. The
transducer is now subjected to a sinusoidal acceleration of 10 ms–2 RMS ±3% using
Type 4294 or 3.16 ms–2 RMS ±3% using Type 4294-002.
5) A calibrated vibration meter will display the transducer output directly in terms of
acceleration, enabling the transducer sensitivity to be determined using:
where:
Scis the calculated transducer sensitivity in pC/ms–2 or mV/ms–2, depending on whether the
vibration meter has a voltage or charge preamplifier
S0is the nominal transducer sensitivity for which the vibration meter is calibrated
Aiis the meter acceleration indication in ms–2
A0is the reference acceleration level: 10 ms–2 for Type 4294 or 3.16 ms–2 for
Type 4294-002
6) If a calibrated voltmeter together with a fixed sensitivity preamplifier is employed for
transducer calibration, the transducer sensitivity may be calculated using:
where:
Scis the calculated transducer sensitivity in pC/ms–2 or mV/ms–2
ScAiS0
⋅
A0
---------------
=
ScV0
A0Ps ⋅
----------------
=

CHAPTER 2
Operation 7
Psis the preamplifier sensitivity in mV/pC or mV/mV
V0is the voltage output from the preamplifier measured in millivolts when the
accelerometer is vibrated at the reference acceleration
A0is the reference acceleration level: 10 ms–2 for Type 4294 or 3.16 ms–2 for
Type 4294 002
7) If a calibrated voltmeter and a conditioning amplifier are used to measure the transducer
charge sensitivity, then an arbitrary mV/unit out range may be selected on the preamplifier.
Multiplication of the mV/unit out setting be the reference acceleration level gives the
correct voltmeter reading. It is then a simple step to adjust the transducer sensitivity dials
on the conditioning amplifier so that the correct voltage reading is displayed by the
voltmeter. The dials on the preamplifier with then indicated the accelerometer sensitivity,
Sc.
8) Any significant departure of the calculated value of Sc from that shown on the transducer
calibration chart is indicative of a faulty transducer.

Calibration Exciter Types 4294 and 4294-002 – User Manual8

9
Chapter 3
Specifications
3.1 Compliance with Standards
The CE marking is the manufacturer's declaration that the product meets the requirements of the
applicable EU directives
RCM mark indicates compliance with applicable ACMA technical standards – that is, for
telecommunications, radio communications, EMC and EME
China RoHS mark indicates compliance with administrative measures on the control of pollution caused
by electronic information products according to the Ministry of Information Industries of the People’s
Republic of China
WEEE mark indicates compliance with the EU WEEE Directive
Safety EN/IEC 61010–1: Safety requirements for electrical equipment for measurement, control and laboratory
use.
UL 61010B–1: Standard for Safety – Electrical measuring and test equipment.
EMC Emission EN/IEC 61000–6–3: Generic emission standard for residential, commercial and light industrial
environments.
EN/IEC 61000–6–4: Generic emission standard for industrial environments.
CISPR 22: Radio disturbance characteristics of information technology equipment. Class B Limits.
FCC Rules, Part 15: Complies with the limits for a Class B digital device.
EMC Immunity EN/IEC61000–6–1: Generic standards – Immunity for residential, commercial and light industrial
environments.
EN/IEC 61000–6–2: Generic standards – Immunity for industrial environments.
EN/IEC 61326: Electrical equipment for measurement, control and laboratory use – EMC requirements.
Note: The above is only guaranteed using accessories listed in the Product Data sheet for Type 4294
and 4294-002 (BP 2101).
Temperature IEC 60068–2–1 & IEC 60068–2–2: Environmental Testing. Cold and Dry Heat.
Operating Temperature: 10 to 40°C (50 to 104°F) for 10 ms–2 reference within ± 3% and
3.16 ms–2 reference within ± 3%
–10 to +55°C (14 to 131°F) for 10 ms–2 reference within ± 5% and 3.16 ms–2 reference within ± 5%
Storage Temperature: –25 to +70°C (–13 to +158°F)
IEC 60068–2–14: Change of temperature: –10 to +55°C (2 cycles, 1°C/min.)
Humidity IEC 60068–2–78: Damp Heat: 90% RH (non-condensing at 30°C (86°F))
Mechanical
Non-operating:
IEC 60068–2–6: Vibration: 0.3 mm, 20 ms–2, 10–500 Hz
IEC 60068–2–27: Shock: 1000 ms–2
IEC 60068–2–29: Bump: 1000 bumps at 400 ms–2
Enclosure IEC 60529: Protection provided by enclosures: IP 54

Calibration Exciter Types 4294 and 4294-002 – User Manual10
3.2 Specifications
4294 4294-002
Dynamic Characteristics
Frequency (Hz) 159.15 ± 0.02%
Acceleration (ms–2 (RMS)) 10 ± 3% 3.16 ± 3%
Velocity (mms–1 (RMS)) 10 ± 3% 3.16 ± 3%
Displacement (μm) 10 ± 3% 3.16 ± 3%
Transverse Amplitude < 5% of main axis amplitude
Distortion 4294:< 2% for 10 to 70 gram load
4294-002: < 2% for 10 to 200 g load
4294 and 4294-002: typical < 7% for 0 to 10 g. Use DB-2996 (10 g) with very light
accelerometers to achieve 2% distortion
Power Requirements
Built-in Battery One 9 V Alkaline Battery QB- 0016 (IEC type 6LR61)
Battery Life Approximately 200 calibrations, each lasting 100 s with automatic switching off at the
end of each calibration
Warm-up Time (Seconds) < 5
Signal Duration (Seconds) 103 ± 1 s with automatic stop
Long-term Stability Better than 1% per year for acceleration, velocity and displacement; better than
10 ppm per year for frequency
Physical Characteristics
Length From bottom to top of calibrator table: 135 mm (5.3 in) – see Fig.3.1
Diameter With case: 46 mm (1.8 in), without case: 43.5 mm (1.7 in)
Weight 500 g (17.6 oz) including battery and leather case
Transducer Mounting
Maximum Load (gram) 70 200
Mounting Torque (Nm) Max. 0.5
Mounting Thread 10–32 UNF

CHAPTER 3
Specifications 11
3.3 Dimensions
Fig.3.1 Dimensions of Type 4294 without leather case
Fig.3.2 Main dimensions (mm) of the calibrator’s vibration table
43.5 mm
1.7 in
128 mm
5.0 in
135 mm
5.3 in
120527/1
ø14
YM-0437
Helicoil: 10-32 UNF
ø 2.1
Bore ø 5
for
Helicoil
+0.1
-0.0
060049/1

Calibration Exciter Types 4294 and 4294-002 – User Manual12

13
Chapter 4
Service and Repair
Types 4294 and 4294-002 are designed and constructed to provide many years of reliable
operation. However, if a fault occurs that prevents the correct function of the calibrator, then
remove its battery to prevent the risk of further damage. For repair, please contact your local
Brüel & Kjær representative. Under no circumstances should repair be attempted by persons
not qualified in the service of electronic instrumentation.
Recalibration
Periodic recalibration of Types 4294 and 4294-002 is recommended in order to maintain the
high accuracy of the vibration unit, and in order to have proof of traceability. Depending on the
application, a recalibration every 1 – 3 years is recommended.

Calibration Exciter Types 4294 and 4294-002 – User Manual14