Zawada NDT
WIRE ROPE INSPECTION

GP Test Heads
[ GP Measuring Heads ]

Equipment for the Non-destructive Magnetic Testing of Wire Ropes

GP series heads Meraster S.A. sensing heads for NDT wire rope inspection examination non-destructive testing of wire ropes

How 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 applied sensors.
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 area.

General Characteristics

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

Operating 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 on request

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

DIMENSIONS mm	HEAD	SENSOR	ROPES mm	HOLE mm	WG. kg	MAIN APPLICATIONS
630x224x244	GP-1	CI-1a (double coil)	30-90	100	60	Winding ropes in mining winders, carrying and hauling ropes in aerial ropeways
630x224x244	GP-1h	CIH-1a (full)	30-90	100	60
610x192x192	GP-2S	CI-2a (double coil)	20-64	75	45
610x192x192	GP-2Sh	CIH-2a (full)	20-64	75	45
610x193x184	GP-2	CI-2a	20-60	75	44	Special for carrying ropes in aerial ropeways
610x193x184	GP-2h	CIH-2a (full)	20-60	75	44	Special for carrying ropes in aerial ropeways
400x88x150	GP-3Ar	single	10-35	40	18	Hauling ropes in aerial ropeways and funicural railways, ropes in drilling rigs and cranes
400x88x150	GP-3Arh	double, mixed	10-35	40	18
268x66x106	GP-4	single	10-26	33	6.3	As above
282x66x68	GP-5	single	8-15	20	5	Ropes in cranes
188x152x92	GP-6-4	4singles	8-14	20	8.5	Four-rope lift instalation
188x222x92	GP-6-6	6singles	8-14	20	12.5	Six-rope lift instalations