Gefran RK-2 Data Sheet

RK-2

CONTACTLESS MAGNETOSTRICTIVE LINEAR POSITION TRANSDUCER
WITH FLANGED HEAD
(ANALOG OR START/STOP OUTPUT)

Main characteristics

• Absolute transducer

• Strokes from 50 to 4000mm (RK-2-_ _ _ _ -N/E/S)

• Digital output RS422 Start/Stop (RK-2-_ _ _ _ -S)

• Direct analog output (RK-2-_ _ _ _ -N/K/E)

• Operating temperature: -30...+90°C

• Resistance to vibration (DIN IEC68T2/6 20g)

• Power supply 18Vdc...30Vdc

• Optional 12Vdc power supply (RK-2-_ _ _ _ -K)

• The digital version (RK-2-_ _ _ _ -S) allows the remote
connection (max. 50 m) of optional electronics for use of
advanced analog (EKA)

Contactless linear position transducer with magneto­strictive technology: the absence of electrical contact
on the cursor eliminates problems of wear and con­sumption and guarantees almost unlimited life.

The head’s flanged shape and small size make the

RK-2 series ideal for applications requiring installation
completely inside the hydraulic cylinder.

The overall dimensions of the sensor are among the
smallest available on the market.

For the interface signal, you can choose between a
start/stop interface (which allows the use of multiple
cursors) and an analog interface that gives the displa­cement of a single cursor (available in the several ran­ges in Voltage or Current).

Excellent linearity, repeatability, resistance to mechani­cal vibrations and shocks complete the product’s speci­fications overview.

TECHNICAL DATA

Model

from 50 to 4000 mm (max. 1200 mm RK-2-_ _ _ _-K)

Measurement taken

Displacement

Position read sampling time (typical)

1 ms

Shock test DIN IEC68T2-27

100g - 11ms - single shock

Vibrations DIN IEC68T2-6

20g / 10...2000Hz

Displacement speed

≤ 10 m/s

Max. acceleration

≤ 100 m/s

Resolution

Infinite, limited by noise (10µm)

Working pressure

350 bar (peak max 500 bar)

Nominal power supply

18...30Vdc opz. 12Vdc (RK-2-_ _ _ _-K)

Max. power ripple

1Vpp

Output signal

Start/Stop (RK-2-_ _ _ _ -S)
0,1...10,1Vdc (RK-2-_ _ _ _ -N)
0,1...5,1Vdc (RK-2-_ _ _ _ -K)

4...20mA (RK-2-_ _ _ _ -E)

Max. analog output load

5KΩ

Output current consumption

max 40 mA (load on start/stop output:300 Ω)

Electric isolation

100 Vdc

Protection against polarity inversion

YES

Protection against overvoltage

YES

Protection in hydraulic circuit area

IP67

Operating temperature

-30°…+90°C for strokes ≤ 2500mm and power supply ≤ 24 Vcc

otherwise -30...+70°C

Storage temperature

-40°…+100°C

Coefficient temperature

0.005% FS / °C

2

displacement

MECHANICAL DIMENSIONS

L (total length)

M4 thread
6mm depth

63.5 32 36

No active

zone

10

CE (electrical stroke)

Model

No active

zone

X

0

ø 33 h8-0.039

Magnet

4

Detail X

1.3 4.5 2.8

90°

ø 28.9 ±0.05 ø 31.6

MOUNTING INSIDE A CYLINDER

ø 13.5 min

38 min.

27.4 max 15 min

fixing screw seat

ISO 7434-M4x10-N

+0.09

ø 33 E8 +0.05

non-magnetic
spacer

magnet

R min. 10mm

ø 27

cable clamp for
cable ø 5-6.5mm

M12x1.5
ø8 max

Sv 1x60°

For RK-2-....-E version

the quote must be 30mm

cable clamp for
cable ø 5-6mm

ELECTRICAL / MECHANICAL DATA

Model

Electrical stroke (C.E.) mm Model

Independent linearity < ± 0.02% F.S. (Min. ± 0.060 mm)

Max. dimensions (L) mm Model + 131.5 (excluding cable)

Repeatability mm < 0.01

Hysteresis < ± 0.005% F.S.

Sampling time msec 1 (1.5 for strokes from 1100 to 2000) (2 for strokes from ≥2000)

50 100 130 150 200 225 300 400 450 500 600 700 750 800 900 1000

1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000

ELECTRICAL CONNECTIONS (RK- 2 - _ _ _ _ - S)

RK-2-_ _ _ _ -S Cable

Output (+) Gray

Output (-) Green

Input (+) Yellow

Input (-) Pink

Power supply + Brown

Power supply
GND Blue

15V

Controller

OP

Transducer

SP

N.C.

N.C.

Output (-)

IN

Output (+)

Input (-)

IN

Input (+)

24V

Power GND

Control system

ELECTRICAL CONNECTIONS (RK- 2 - _ _ _ _ - N/K/E)

RK-2-_ _ _ _ -N RK-2-_ _ _ _ -K RK-2-_ _ _ _ -E Cable

Output 0.1...10.1Vdc Output 0.1...5.1Vdc Output 4...20mA Yellow

Output GND Output GND Output GND Pink

Power supply + Power supply + Power supply + Brown

Power supply GND Power supply GND Power supply GND Blue

IMPORTANT: in case of cable lenggth shortening, after cutting the cable take care of soldering and insulating the green
and grey wires together

DIGITAL OUTPUT RK- 2 - _ _ _ _ - S

Series RK-2-_ _ _ _ -S magnetostrictive transducers supply
digital outputs in START/STOP format with RS422 differential
serial transmission.
The transducer requests an Initialisation pulse that launches
sampling. The following pulses are transmitted on the outputs:

Start: the Initialisation pulse retransmitted
Stop: the pulse corresponding to the position of each magnet.

The time between the Start pulse and the subsequent Stop pul­ses is proportional to the position of each magnet according to
the “Magnetostrictive wave propagation speed” constant, equal
to about 2900 m/Ssec.

P=
Time * 2900m/Sec

The correct propagation speed for each product is shown on
the product label.
Resolution in terms of metres is linked to the resolution used to measure time

The distance between Start

and Stop is proportional to
the position of the magnet

N cursor

1 µSec (1MHz ) ==> 2.9 mm
10 nSec (100 MHz ) ==> 0.029mm
1 nSec (1GHz ) ==> 2.9 µm

The measurement reference is the leading edge of the pulse.
Optimum width of the interrogation pulse is 3µSec, but the transducer works correctly for times from 1.5 to 5µSec