ED-800 PORTABLE VARIABLE
EDDY CURRENT INSTRUMENT
EQUIPMENT SPECIFICATION ES-104
1.0 Description
1.1 The Model ED-800 is a
variable frequency eddy current instrument, with a cathode ray tube readout,
that detects homogeneity and conductivity changes in magnetic and nonmagnetic materials
instantaneously. The instrument is
battery operated, light weight, and can be used in the manufacturing shop, in
the field, and in the laboratory with a wide selection of probes and coils
common to standard Centurion NDT units (ED-520, ED-530, ED-525, ED-535, FW-450,
and ED-810).
1.2 The instrument will detect surface and
subsurface defects in both magnetic and nonmagnetic materials. Defects cause voltage variations that are
amplified and displayed on the CRT in the ‘store’ or ‘nonstore’ mode. This readout provides maximum information on
eddy current behavior within the material being tested in terms of phase and
amplitude simultaneously. As a matter
of convention, liftoff is displayed as the horizontal line of the CRT and the
crack indication is an upward or downward slanted line that meets the
horizontal at the right of the extremity of the trace. The severity of the defect is represented by
how far the slanted line deflects above or below the horizontal. The phase relationship is the angle between
these two lines.
1.3 The ED-800 will sort classes
of materials according to hardness alloy, carbon content, tensile strength, and
grain structure. Also, it will measure
coating thickness, sheet thickness and measure relative conductivity of critical
materials.
1.4 The Box Gates permit simplified
discrimination between signals produced by most defects and by those
unimportant variations in the part being tested. With the “flying dot” display, changes in phase or amplitude in eddy
currents are reflected by movement of a spot on the CRT screen. With the box gates, an illuminated,
box-shaped area variable in size and location is presented on the screen. Using a sample part with a known flaw, the
box may be positioned on the screen so that the flying dot enters the box area
when deflected by the flaw signal. Entry of the dot triggers the gate,
producing a signal, which can set off a visual or audible alarm, or trigger
automatic rejection of a defective part for later examination. Thus, only defects of a known type or
severity will be detected.
2.0 Mechanical and Construction
2.1 The instrument consists of solid-state
circuitry, printed circuit boards, cathode ray tube, and battery housed in an
aluminum case with a handle that swings around the instrument from top to
bottom.
2.2 Dimensions: 5.5” (14.0
cm) H x 11” (27.9 cm) W and 13” (33.0 cm) D.
2.3 Weight: 16 lb. (7.2 kg)
2.4 The instrument will operate within the temperature range of 0o
F to 120o F, at 85% relative humidity, maximum.
2.5 The die cast handle locks in 14
convenient positions around the instrument from top to bottom. It provides an easy means of carrying the
instrument and allows tilt on flat and curved surfaces for convenient viewing
of CRT patterns and accessibility to controls.
With handle in the vertical position, the instrument can be hung from an
overhead hook.
2.6 Removing
the top and bottom covers facilitates servicing the instrument. All circuitry is exposed and the instrument can be operated in
the pulled-apart mode.
2.7 The front panel probe connectors are twin BNC and a four-pin
microphone.
2.8 A trapdoor is located on top
of the instrument and provides a well for balance, mode, and position and box
gate controls. A hinged cover with
latch protects the controls from accidental movement
and dirt from the environment.
2.9 A protruding bezel
completely surrounds the front on the instrument and protects the controls and
CRT while the instrument is being moved from one location to another.
2.10 The bezel surrounding the CRT may be
removed, thus allowing replacement of the graticule in front on the CRT and
cleaning when necessary.
2.11 There are four rugged feet on the bottom of
the instrument that act as shock mounts and protect the unit from debris and
other foreign materials that may be present on surfaces on which the instrument
is placed.
2.12 The TH-1021 can be magnetically fastened to a steel plate on the
top well cover of the ED-800.
3.0 Electrical and Performance
3.1 The instrument is powered from an
integral rechargeable nickel-cadmium battery, or 115/230 volt, 50/60 Hertz,
single phase power line through a battery eliminator in the battery
compartment, or from the power line (115/60/1) through the charger while the
battery is being charged. The power
consumption is 7.5 watts.
3.2 Battery life per charge is approximately 8 hours. Recharge time is approximately 14 hours.
3.3 The instrument has a
variable frequency range from 100 Hz to 2.5 MHz. It operates with two probes, a test probe and a reference probe
(not for testing but serves as an arm in the eddy current bridge to facilitate
balancing). Any of the standard
Centurion NDT probes of our current instrument line (ED-520 series, ED-530
series, FM-140) may be used. In cases where
the probe connector does not match the ED-800 BNC front panel connectors, adapters
can be obtained.
3.4 The standard battery charger
operates from 115 volt, 60 hertz, single phase line current and charges a
single battery in the instrument or removed from the instrument.
3.5 The cathode ray tube of the
ED-800 is a storage monitor that shows a flying dot display featuring random
access memory with storage locations allocated to the tube face. As such, the instantaneous movement of the dot may be viewed on the tube face
without storage or the dot movement may be stored on the tube face. When a suitable pattern, representing the
limits of a given test, has been established and stored, the instrument can be
switched back to the instantaneous mode.
As the test is being made, the stored information remains on the tube
face and the instantaneous flying dot can be superimposed on the tube face for
matching the known to the unknown.
3.6 The TH-1021 gate will monitor either the
horizontal or vertical movement of the moving dot on the CRT. The
TH-1021 tone changes with dot movement.
3.7 The box gates may be adjusted to any rectangular size and
moved to any position on the CRT.
4.0 Operation
4.1 There are two Frequency
controls, a coarse switch and a vernier, for establishing a suitable test
frequency from 100 Hz to 2.5 MHz.
4.2 The Sensitivity control varies the gain of the instrument over a range
of 100:1.
4.3 The Phase control allows rotation of the display from 0 to 360o.
4.4 The Probe Drive controls the
power to the probe and is coupled to an Overload light that turns on when the
setting is too high for optimum performance.
4.5 The Hi-Lo Impedance switch matches the instrument to the probe for
optimum performance.
4.6 Focus and Intensity controls optimize the CRT presentation for ease of
viewing.
4.7 The Erase pushbutton erases the data
stored in the unit’s memory and clears the display. It operates like the erase on a storage oscilloscope. The Store/Nonstore control is used to shut off
further storage of CRT information while retaining anything already
stored. This control is quite useful
for sorting because information representing test limits can be stored and then
the movement of the dot, in the nonstorage mode can be observed and related to
these limits.
4.8 There are 3 modes of instrument balance
available to the operator. Manual
Balance sets the dot in a specific location on the CRT. Once located, the dot will hold its position
without drift. This mode is most useful for sorting because it is not necessary to
recalibrate to a reference sample periodically because of “dot drift”. The Hold mode requires the instrument to be
balanced by actuating the “Push to Balance” control, which brings the dot to
the desired location. The setting will
remain fixed for several minutes but will slowly drift requiring balancing
periodically. In the Auto mode, the
trace will balance itself continuously within one second. This mode is particularly useful for crack
detection because it will keep the probe balanced on crack-free material.
4.9 The position controls, within the top
well are used to locate the dot position when in the “Hold” balance mode of operation.
4.10 See ES-105 for operation of the TH-1021 Gate.
4.11 The box gates blink on and off when the flying dot enters the
rectangle.
5.0 Order Reference
5.1 Model ED-800 Portable Crack Detection and
Sorting Instrument, P/N 219860 in
metal enclosure with handle and including:
+ High Resolution Storage Board
+ Dual Box Gate Board
+ Form 20509 Instruction Manual
5.2 Standard Accessories
5.2.1 Battery Eliminator, P/N 212212. Fits into battery compartment and permits operation of instrument
on 115/230, 50/60 single-phase line current.
5.2.2 Rechargeable
Nickel-Cadmium Battery Pack, P/N 212037.
5.2.3 Battery Charger/Eliminator, P/N 217554. Battery charger will operate instrument from line power and also
charge battery inside or outside instrument on 115/230; 50/60; single phase
line current.
5.3 Addendum Accessories
5.3.1 Model
TH-1021 Audio Gate, P/N 211940A
5.3.2 Model
HS-50 Bolt Hole Scanner, P/N 222650
5.3.3 Carrying
Case, vinyl material, protects unit when not in use, P/N 219888
5.3.4 Reset Control Assembly for remote balance of instrument, P/N 213755
5.3.5 Foot Switch Assembly for remote balance of instrument, P/N 218823
5.3.6 Dual
Channel Strip Chart Recorder, P/N 519345
5.3.7 Cable
Adapter for operation with FW-450 Series Coils (including cable), P/N 213853
5.3.8 Adapter for connection of cross-coil probe, P/N 206218, to the
dual BNC connectors on the ED-800, P/N 212099
5.3.9 Aluminum
Test Block with single slot .015” deep, P/N
205156
5.3.10 Aluminum Test Block with three slots, .008”, .020”,
and .040” deep, P/N 207066
5.3.11 Balancing Load, medium frequency, P/N 209730
5.3.12 Balancing Load, high frequency, P/N 209735
5.3.13 Consult the probe catalog
for the many standard probes and coils available for use with the ED-800. The ED-800 design requires that two probes or two coils must be connected to
the instrument for proper operation. It
will not work properly with only one probe or coil. In some cases, an adapter is required between the end of the
probe cable and the instrument connector.
Consult factory to determine if a
balance load is available for the desired probe.
6.0 References
6.1 Instruction Manual, Form No. 20509
6.2 ES-105 for TH-1021 Audio Gate
6.3
ES-103 for HS-50 Bolt Hole Scanner
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