MD120 Wire Rope Defectograph:
Optional Hardware and Software for PC
GP Measuring Heads
Equipment for the Non-destructive Magnetic Testing of Wire
does the sensing head work?
During testing the sensing head ensures that the running
sector of the wire rope is brought to a condition close to magnetic saturation
and provides signals from its sensors to the Meraster MD120
tester. Sensors in the head detect magnetic leakage flux due to external
or internal defects in the rope, these defects can be as small as 0.05
% of the rope's cross-sectional area. Heads are intended to detect localised
losses, eg from broken wires and pitting corrosion; to detect distributed
loss of metallic cross-sectional area, due to corrosion, wear and abrasion;
and to estimate the depth of the localised loss position inside the rope.
Test results are not affected by plastic coating, grease, etc. Two-piece
construction makes it possible to test the rope with only one half of the
head, for example testing track rope on the ropeway support This two piece
construction also makes it easier to carry the head (i.e. in two parts).
Detecting capabilities of sensing heads vary between
Meraster applies four categories of sensors in its heads:
One-channel inductive system, a single coil system used in
small heads to correctly detect localised losses.
Two-channel mixed system, a single coil system and Hall-effect
sensing system used in medium heads to detect localised losses and the
distributed loss of metallic cross-sectional area.
Two-channel inductive system (CI-..), a double coil system
used in large heads to correctly detect localised losses and to estimate
the depth of the position of the localised loss inside the rope.
Full three-channel system (CIH-..), a double coil system
and Hall-effect sensing system used in large heads to detect localised
losses; to estimate the depth of the position of localised losses
inside rope and to detect the distributed loss of metallic cross-sectional
Application Range: Measuring a signal source in testing
of wire ropes made of ferromagnetic steel
Output: Inductive coil signals vary between defect,
rope and sensor sizes and testing speeds, in the range microvolts to volts
AC.; Hall-effect sensor signal is typical on microvolts/milivolts level
with larger DC component
Temperature Range: -25 to +40°C
Supply: Not required for inductive coil sensors.
Controlled supply required for Hall-effect sensors.
Lead length: 10 m is standard, or longer
RI Rope Length Converter
In order to measure the running rope length (and speed
of relative movement), heads may be equipped with a special transducer
to indicate rope/head movement as an electric signal. Meraster recorders-defectographs
also use it to synchronise the strip chart feed with the rope/head travel
and to compensate for speed influence on the inductive coil signal.
Output : Encoder type 2 x 100 pulses/m ; 0/+12V
Supply : +12V/+5V dc
Standard lead length: 10 m
Bold characters - standard heads, others on request
||CI-1a (double coil)
||Winding ropes in mining winders, carrying and hauling
ropes in aerial ropeways
||CI-2a (double coil)
||Special for carrying ropes in aerial ropeways
||Hauling ropes in aerial ropeways and funicural railways,
ropes in drilling rigs and cranes
||Ropes in cranes
||Four-rope lift instalation
||Six-rope lift instalations