SENSOR SOLUTIONS /// GCT Series Rev 6 07/2017
Page 1
FEATURES
All-welded stainless steel
construction
Resistant to harsh environments
MS type connector (MIL-C-5015)
Long cycle life
Reverse polarity protection
Calibration certificate supplied with
each unit
Air extend/spring retract available
(Consult factory)
APPLICATIONS
Bridge expansion monitoring
Pipeline vibration monitoring
Valve position
Compressor feedback
Noisy environments / long cable
runs
In-process measurements (feedback
loop with PLC or CNC controller)
GCT SERIES
4 to 20mA loop Gage Heads
SPECIFICATIONS
4-20mA loop, two wire operation
Hermetically sealed housing
25 µ-inch [0.6 µm] repeatability
IEC IP68 rating to 1,000 PSI [70 bars]
Stroke ranges from 0.250 up to 2 inches
Reverse polarity protection
Hardened tool steel contact tip
High side load resistance
The GCT Series heavy-duty gage heads enable high performance in
environments containing moisture, dirt, and fluid contaminants. With a
spring loaded LVDT, a precision linear bearing, and internal signal
conditioning electronics o
perating on a 4 to 20mA loop, the GCT is
ideal for difficult industrial environments and remote locations where
sensor power is not readily available and long cable runs are
expected. The 4-20mA signal is less susceptible to EMI and RFI
interference than low amplitude AC or DC signals.
These robust gage heads allow measurements over stroke ranges
from 0 to 0.250 inch [6.35mm] up to 0 to 2 inches [50.8mm]. The spring
force is typically 9oz [255 grams] at fully compressed electrical stroke.
A removable black-chromed, hardened tool steel tip is threaded (4-
48UNF-2A) to the working end. Internal construction prevents the core
and shaft from rotating as they move longitudinally. The integral
electrical connector (welded) provides for easy installation and allows
replacing a damaged cable without sacrificing the sensor. Installation
and adjustment are facilitated by an external ½-20 mounting thread
and the two locknuts supplied with each unit.
Like in most of our LVDTs, the GCT windings are vacuum
impregnated with a specially formulated, high temperature, flexible
resin, and the coil assembly is potted inside its housing with a two-
component epoxy. This provides excellent protection against hostile
environments such as high vibration and shock.
The ruggedness, long life cycle, and very high reliability of the GCT
Series provide the lowest cost of ownership over the life of the
equipment onto which they are installed. The one-piece front end
(barrel which contains the bearing assembly), machined from solid
stainless steel bar, coupled with a bronze bushing, has far greater
resistance to bending forces and side loads compared to other
designs. This is particularly important on the longer stroke versions; it
reduces the common risk of probe damage/bending during installation
or maintenance of industrial equipment. The GCT Series designs also
require fewer parts and weld joints, thereby increasing overall
structural integrity and reliability.
GCT SERIES
4 to 20mA loop Gage Heads
SENSOR SOLUTIONS /// GCT Series Rev 6 07/2017
Page 2
PERFORMANCE SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
Parameter
GCT 250
GCT 1000
GCT 2000
Stroke/gaging range
0.25 [6.4]
1 [25.4]
2 [50.8]
Sensitivity, mA per inch
64
16
8
Loop supply voltage
10.5 to 28VDC
Output
4 to 20mA, two wire loop (Output increases when core is displaced towards connector)
Output at null position
12mA (null position is defined as the mid-stroke position)
Maximum loop resistance
540 ohms @ 24VDC (see loop resistance chart below)
Non-linearity
±0.5% of FR, maximum
Output noise and ripple
25 µA RMS maximum
Repeatability
25 µ-inch [0.6 µm]
Stability
0.1% of FSO after 30 minute warm up
Temperature coefficient of sensitivity
0.022%/°F [0.04%/°C]
Frequency response (dynamic)
15 Hz, maximum
ENVIRONMENTAL SPECIFICATIONS & MATERIALS
Operating temperature
-13°F to +185°F [-25°C to 85°C]
Survival temperature
-65°F to +250°F [-55°C to 125°C]
Shock survival
250 g (11ms half-sine)
Vibration tolerance
10 g up to 2kHz
Housing material
AISI 400 Series stainless steel
Electrical connector
6-pin MS type connector (MIL-C-5015)
IEC 60529 rating
IP68 to 1,000 PSI [70 bars] with use of proper mating connector plug
Notes:
All values are nominal unless otherwise noted
Dimensions are in inch [mm] unless otherwise noted
FR: Full Range is the stroke range, end to end; FR=S for a 0 to S stroke range
FSO (Full Scale Output): Largest absolute value of the outputs measured at the ends of the range
WIRING SCHEMATIC & LOOP RESISTANCE
0
100
200
300
400
500
600
700
10 12 14 16 18 20 22 24 26 28
Loop supply voltage, VDC
Max loop resistance, Ohms
10.5
540