ED-520Automatic Eddy CurrentFlaw Detector

Special Features

Proven, reliable microprocessor-based circuit design

Highly sensitive resonance-type eddy current instrument

Automatic, pushbutton selection of operating frequency and balance

Wide selection of probes and coils - interchangeable with existing equipment

Variable frequency range from 55 KHz to 220 KHz

Built-in threshold circuit includes an indicating lamp and an audible alarm

Extremely versatile, yet simplified operation

Dust-proof, weather resistant rugged aluminum enclosure for operation under most environmental conditions

Includes test block and pencil probe

ApplicationsThe model ED-520 eddy current instrument is an electronic device that will locate surface and near-surface discontinuities in non-magnetic materials. It also finds surface defects in magnetic materials, where permeability is relatively constant throughout the test area. In addition, the ED-520 will sort classes of materials according to such properties as hardness, alloy type, carbon content, heat treat condition, tensile strength, and grain structure (where these relate to changes in the magnetic and electrical characteristics of the test part).

With proper standards, electrical conductivity may be evaluated. This often relates to the tensile strength of many aluminum and magnesium alloys. The instrument can also be used to measure the thickness of thin, non-magnetic sheets, as well as conductive and nonconductive coatings (when used with suitable standards).

The ED-520 is widely used in military and commercial aircraft testing as well as process control, receiving inspection, research, and maintenance. Its compactness, ease of operation, and consistent precision make the ED-520 valuable for testing in foundries, heat treat shops, and manufacturing plants - wherever accurate data must be obtained quickly to establish fatigue or product reliability. The ED-520 features battery operation for extended field use. It is easily recharged for the AC line, using the supplied AC charger.OperationThe push-button controlled ED-520 instrument utilizes the eddy current principle, whereby induced currents are affected by changes in test part characteristics and homogeneity. Variations in material conductivity, permeability, or physical characteristics cause impedance changes in the test probe or coil attached to the bridge circuit. Such an impedance change causes the bridge to become unbalanced, as indicated by a change on the front panel meter.

Initially, the probe (or coil) is tuned to the specific geometry, conductivity, and permeability of the test system, through adjustment of the lift-off/frequency control. This adjustment for lift-off is especially important in reducing irrelevant meter reading due to surface coatings, roughness, oxides and rocking or wobbling of the probe during testing.

With a full charge, the ED-520 can operate on batteries continuously for a least 8 hours. Recharging takes 10-14 hours.

DescriptionThe ED-520 is a portable, self contained electronic instrument offering high sensitivity, versatility and ease of operation. Either manual of automatic adjustment of frequency or balance controls allows the instrument to be set for highest sensitivity on various parts with various probes or coils. The manual controls can also be operated in conjunction with pushbuttons to permit "fine tuning" after automatic setup.

Sensitivity:Single-turn control for continuous adjustment of the gain between push-button selectable settings.

Charge:LED indicates charger is plugged in and battery is being charged.

Frequency:Continually varies adjustment of operating frequency over the range of 55 KHz to 220 KHz. In the automatic set-up mode, used to fine adjust lift-off/frequency.

Balance:Controls the position of the meter needle.

Gate:A rotary switch to select upscale or downscale triggering for the threshold gate The single-turn potentiometer positions where the threshold gate triggers. The LED indicator lights when the gate has been triggered.

Accessory:Analog outputs available for chart recorder; TTL output for relay.

Probe:BNC-type connector for a wide range of probes and coils. All previous ED-520 and ED-530 probes and coils are compatible.

Phone:Earphone connector.

Volume:Determines earphone volume.

Test Block:2024 Aluminum alloy with reference slots of .008", .020" and .040" deep. Used to periodically check the instrument's performance.

Push-Button Controls

BATTery:Depress to read battery status.

ON:Power switch. Embedded LED lights when power is applied.

BALance:Activates the auto-balance function. Will set the meter needle to the desired location on the meter face.

SCAN:Activates the automatic lift-off compensation function.

FREQency:Depress to display operating frequency.

Range:Selects between the three sensitivity levels for the unit.

SpecificationsCase Dimensions:(cover closed): 6" deep x 9" wide x 5" high (15.2cm x 22.9cm x 12.7cm)

Weight:5.5 lbs. (2.48 kg)

Power:Rechargeable Ni-Cad battery. Line operation must be specified to operate 115 or 230V.

Enclosure:Case is made of durable aluminum, cover contains accessory packet

Frequency Range:Variable from 55 KHz to 220 KHz

Readout:Rectangular meter, 3.5" wide. Scale numbered from 0 - 500 in 50 divisions

Environment:0 to 120 at 85% RH

ED-520 PORTABLE EDDY CURRENT INSTRUMENT

EQUIPMENT SPECIFICATION ES-113

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1.0 Description

1.1The Model ED-520 is a microprocessor-based portable, self-contained, electronic instrument which offers high sensitivity, versatility, and simplicity of operation. A continuously variable frequency control tunes an oscillator that drives a bridge circuit, one leg of which contains the test probe or coil.

1.2The instrument will locate surface and near-surface discontinuities in nonmagnetic materials and surface defects in magnetic materials where permeability is relatively constant throughout the test area. The ED-520 will sort both classes of materials according to such properties as hardness, alloy type, carbon content, heat treat condition, tensile strength, and grain structure where these relate to changes in the magnetic and electrical characteristics of the test part. Also, it will measure coating thickness and relative conductivity.

2.0 Mechanical and Construction

2.1Dimensions: 6 (15.24 cm) x 9 (22.86 cm) x 5 (12.7 cm) high (cover closed)

2.2Weight: 5.5 pounds (2.48 kg)

2.3Readout: Rectangular meter, 3.5 (8.9 cm) wide. Scale numbered from 0 to 500 in 50 divisions

2.4The ED-520 is housed in a lightweight, aluminum case fitted with a removable cover and positive action latches. The cover contains an accessory storage pocket for quick storage of probe cable(s), probe(s) and test samples.

3.0 Electrical and Performance

3.1The frequency range is variable from 55 kHz to 220 kHz.

3.2The instrument is operated from a single self-contained, rechargeable nickel-cadmium battery pack or from 115/220 volts AC, 50/60 Hz line power.

3.3Power consumption from the battery is 4.8 volts, DC, at 160 mA and from the line 115 volts, AC, 10 watts.

3.4The battery charger is a separate module with an output of 13.5 regulated volts D.C. The cord is 72 (1.8 m) long.

3.5The batteries are rated for approximately 12 hours continuous operation from the fully charged state, at 70o F, before recharging is necessary. The recharge time required is 10 to 14 hours.

4.0 Operation

4.1The row of pushbuttons located on the bottom of the front panel selects the major operation features of the unit. From left to right, the first group is POWER, MODE refers to the mode of operation, and RANGE refers to the gain setting of the unit.

4.1.1ON -- Pushbutton with integral LED powers the unit. LED lights when power is applied.

4.1.2BATT -- Momentary pushbutton which displays, on the front meter, the charge status of the battery.

4.1.3BAL -- Momentary pushbutton used to bring the meter pointer on scale.

5.1.1 5.1.1 SCAN -- Momentary pushbutton used to set lift-off. Integral LED will light and beeper will sound as the microprocessor is performing the frequency scan.

4.1.5FREQ -- Momentary pushbutton enables the oscillator frequency to be displayed on the front meter.

4.1.6LOW, MED, HI -- Pushbuttons with integral LEDs which light when that particular gain range is selected.

4.2The SENSITIVITY control is a single turn potentiometer used to set the sensitivity level at any point between the RANGE pushbutton settings. Maximum sensitivity is obtained with this control set fully clockwise.

4.3The FREQUENCY control is a ten-turn potentiometer with a locking counting dial. It provides a continuously variable frequency range of 55 kHz to 220 kHz to select the proper operating frequency for lift-off compensation.

4.4The BALANCE control is a ten-turn potentiometer with a locking counting dial. The control adapts the probe used to the bridge circuit and is used to position the meter pointer on the scale.

4.5The ACCESSORY connector allows accessibility to an analog/meter output and the gate/alarm output. Connector pin designations are as follows:

Pin 1: Gate/Alarm Output

Pin 2: Gate/Alarm Output

Pin 3: Analog/Meter Output

Pin 4: 13.5VDC with Charger plugged in

Pin 5: Ground

Pin 6: No Connection

Pin 7: No Connection

4.6The GATE group is used when a threshold gate operation is desired.

4.6.1 The GATE switch is a four position rotary switch marked OFF, DN, UP and

TONE. These positions determine the mode of operation on the threshold circuit. In the OFF position, the threshold gate is inactive. In the DN position, the threshold alarm is triggered as the meter pointer swings downscale. In the UP position, the threshold alarm is triggered as the meter pointer swings upscale. In the TONE position, a tone is heard only through the earphones (not included) that will vary in frequency as the needle on the meter moves.

4.6.2The POS control is a single turn potentiometer that adjusts the point at which the threshold gate activates. As the threshold gate is activated, the LED lights and the internal audio annunciator sounds.

4.7The power connector is where the charger cord is plugged in to power the unit or charge the batteries. Whenever the charger cord is plugged the LED will light.

4.8The PROBE connector is a panel mounted BNC connector used to connect the eddy current probe to the unit.

5.0 Order Reference

5.1

The Model ED-520 Portable Eddy Current Instrument, P/N 220520, in aluminum enclosure, operating on self-contained rechargeable nickel-cadmium batteries including:

Probe Cable, BNC to Microdot

General Purpose Probe

Aluminum Sensitivity Standard

Power Supply/Battery Charger (must specify 110V or 220V)

Operating Manual

5.2 Standard Accessories

5.2.1 Probe Cable, P/N 210816

5.2.2General Purpose Probe, P/N 222296

5.2.3Aluminum Sensitivity Block, .008, .020, .040 deep slots, P/N 225459

5.2.4Battery Charger, 115/50-60/1, P/N 520104

5.2.5 Battery Charger, 220/50-60/1, P/N 520127

5.3Addendum Accessories

5.3.1General Purpose Miniprobe, 1-1/8 long x 5/16 diameter, P/N 207067

5.3.2General Purpose Probe, 4 long x 3/8 diameter, P/N 062743

5.3.3General Purpose Probe, 4 long x 1/8 diameter, P/N 223400

5.3.4Various Wheel Bead Seat Probe Holders

5.3.5Various Bolt Hole Probes (Consult Probe Catalog)

5.3.6Various Hemispherical Probes (Consult Probe Catalog)

5.3.7Various Sorting Coils (Consult Probe Catalog)

5.3.8Strip Chart Recorder, P/N 519354

5.3.9Absolute Pencil Probe Kit, P/N 219586

consists of :1 ea. P/N 223400 Pencil Probe

1 ea. P/N 223695 Right Angle Pencil Probe

1 ea. P/N 222296S Short General Purpose Probe

1 ea. P/N 210816 Probe Cable

6.0 References

6.1Instruction Manual, Form No. 25004, effective January 4, 2001

6.2Price Pages EC-55