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NDT of wire ropes, wire rope inspection, examination in-service

MD120 Wire Rope Defectograph:

PC Card,
Optional Hardware and Software for PC

Measuring Heads

Wire Rope



The Instrument Set for Non-destructive Magnetic Testing of Wire Ropes

MD120 photo  Meraster S.A. instrument for NDT wire rope inspection examination non-destructive testing of wire ropesSince 1979, Meraster has supplied instruments to estimate the in-situ deterioration of wire ropes around the world.

 The operation of our NDT instruments is based on permanent magnet method, which was developed in Poland and is used throughout the world. Meraster's standard range of sensing measuring heads can be used for ropes ranging from 8 to 90 mm diameter. Custom designed heads are also available. For smaller ropes our MD-20 hand-held head-tester can be used.

 Recently developed by Meraster, the MD120 recording system includes a specially designed portable chart recorder with additional data recording which can be transferred to a computer. This unique instrument has been designed as a helpful and comfortable tool, to meet the special needs of rope experts in industrial environments.

 Unique features:

  • Detecting the position of defects throughout the rope's entire length and depth
  • Using mathematical integral method for easier readout of high density defects
  • Zoom replay of recorded defects

  • :
  • Diagram solid state memory
  • Computer interface
  • "Settings with rope code" memory
MD120 Defectograph uses today's knowledge and technology to provide the maximum possible information that can be obtained from a rope in situ under non-destructive testing.

MD120 and GP photo  Meraster S.A. instruments for NDT wire rope inspection examination non-destructive testing of wire ropes


Rope size range
GP series standard heads diameter  from 8 to 85 mm 
heads GP-1 type from 30 to 85 mm
heads GP-2 type from 20 to 60 mm
heads GP-3 type from 10 to 30 mm
head GP-4  from 10 to 26 mm
head GP-5  from 10 to 15 mm
heads GP-6 type from 8 to 14 mm
Hand-held tester MD-20 as a head from 8 to 22 mm
GM series light-weight heads from 10 to 90 mm 

Rope types
wire ropes made of ferromagnetic steel, any form of construction

 Detected rope defects

  • defects characterised by stepwise changes in rope cross-section, i.e. broken wires, pitting corrosion, etc., are detected using inductive sensors in all heads
  • larger losses in a rope's metallic cross-section, i.e. wear, corrosion in longer length etc. are detected using additional Hall-effect sensor in GP-1(h), GP-2(h),

  • GP-3(h) and GM series heads
  • real distortion
Able to detect
all important defects to estimate rope deterioration; maximum sensitivity may be as high as 0.05% of nominal rope metallic cross-sectional area (but such defect readability depends on the rope's construction)

 Defect positioning on rope length
with rope length converter RI, mounted in heads GP-1 type, GP-2 type, GP-3 type, GM or separate for others

Defect positioning of depth inside rope
with heads equipped with double inductive sensors ("inner" and "outer"), i.e. heads GP-1 type, GP-2 type, GM

 Operating conditions
Temperature from -25° to + 40° C 
for recording on paper from 0° to + 40° C 
Relative humidity to 95% 
for recording on paper from 25 to 85%

Dimensions and weight of measuring heads
See: "GP Measuring Heads", "GM Measuring Heads", "MD-20 Wire Rope Tester"


Application range
This instrument is intended to record signals from magnetic sensing heads for testing wire ropes. It may also be direct applied to recording other electric signals within its sensitivity range 1mV/mm to 3.2 V/full scale or it may be customised to record within another required range, from 50 µV/mm.

 Main modes

  • chart feed at constant selectable speed
  • chart feed synchronous to rope movement
Recording channels
  • 4 measurement channels -
    • 2 channels of inductive sensors (coils) signals,
    • 1 channel of Hall-effect sensor signal,
    • 1 channel of mathematical integration of the inductive signal,
  • rope length printout in meters by 5 cm of chart,
  • time marks every 1 second and 10 seconds
  • printout of recorder settings, rope code settings, time and date

Wire rope test chart

printed chart example, Meraster NDT, wire rope inspection, examination in-service

Recording method
Thermal array line printing head, printing on thermal paper on a roll 112 mm x 25m

  • resolution 8 dots/mm
  • channel format - overall width 103 mm
    • Induction channels ± 18 mm each
    • Hall channel ± 9 mm
    • Integral channel 9 mm
  • grid every 1mm and 10 mm in separate channels
Rope speed range at compensation of speed influence to inductive sensor signals
0.05 to 10 m/s

Displayed rope speed range
0.05 to 9.99 m/s by 0.01m/s, over range indicated

 Rope length display range 1 to 9999 m by 1 m reversible, up/down counting option, initial length setting capability

 Length converter input
2 x 100 pulses/m (type RI)

 Paper chart drive
1, 2, 5, 10 mm/m of rope or 1, 2, 5, 10 mm/second at synchro-feed rope speed should be limited
at 1 mm/m to 7.0m/s
at 2 mm/m to 7.0m/s
at 5 mm/m to 3.6m/s
at 10 mm/m to 1.8m/s
"Zoom replay" ratio 20 mm/m of rope or mm/s

"Zoom replay" memory capacity 18.75 m of rope or 18.75 seconds of recording

 Acoustic signal of rope defect level
10, 20,....to 90% of full scale of the inner sensor channel (beeper and also headphones)

 "Settings & Rope Code" Memory
Capacity 100 items


  • liquid crystal display 2 x 40 characters
  • RUN or STOP
  • LED indicator POWER ON
  • LED indicator PAPER OUT
  • multicolour LED indicator of battery charging
Diagram memory (optional Memory Card)
Type: SRAM Memory Card
PCMCIA type I or II, 
Capacity:  512 kB to 4 MB, i.e.
300 to 2400 m of rope at synchro mode
or 300 to 2400 seconds (40 min) of recording
Recorded data: 3 signal channels + integral channel
at sampling rate 2.5 mm or ms
recorder settings, rope code, time, date
rope length counter
Data replaying: printing selected sectors with MD120 
with computer and software tools 

Required interface for data transfer from diagram memory to the computerPCMCIA port & professional, byte level software driver

 Sensitivity range
Outer and inner coil channels

  • sensitivity at constant chart feed in mm/s and at synchro mode (mm/m), for rope speed 1m/s: 1, 2, 5, 10, 20, 50, 100, 200 mV/mm , at input resistance 21.5 kohm
  • actual sensitivity at synchro mode
    • for rope speed 0.05 to 10m/s depends on: "nominal sensitivity" x "value of rope speed in m/s"
    • at speed less than 0.05 m/s: as for 0.05 m/s (max. sensitivity 1 mV/mm x 0.05 = 0.05 mV/mm)
Hall-effect sensor channel
  • 0.1, 0.2, 0.5, 1, 2, 5, 10, 20 mV/mm
  • differential input voltage

  • with DC component cutting, 0-400 mV
Integral of inductive signal
  • 4 sensitivity levels
  • running integral range 0.1 to 9.99 m or s
  • AC Mains 220 V, 80 VA; other AC Mains voltages on request
  • DC 12 V, 50 W
  • Internal rechargeable battery for 4-6 hours of operation without external power
    • deep discharge protection
    • recharging while external power is connected
47.5 x 37 x 17.5 cm

with standard accessories 13 kg