Eurotherm Q438 Data Sheet

Q438-0000

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ACTIONI/Q

®

Q438

DC Powered Potentiometer Input

Signal Conditioner

Provides a DC Output in Proportion

to a Potentiometer Input

 Accepts Potentiometers from 100 Ohms to 100k Ohms
 Wide Ranging Zero and Span
 ASIC Technology

Description

The Q438 is a DIN rail mount, potentiometer input signal condi­tioner with 1800VDC isolation between DC power and the input/
output circuitry. The input provides a constant voltage and is
designed to accept any three-wire potentiometer from 100 ohms to
100k ohms. The field configurable output is switch selectable
providing a 0-5V, 0-10V, 0-1mA, 0-20mA or 4-20mA DC signal. Wide
ranging, precision zero and span pots, used in conjunction with DIP
switches, allow 80% adjustablity of offset and gain to transmit a full
scale output from any 20% portion of the potentiometer input.

Application

The Q438 is useful in transmitting process control setpoints to remote
PID controllers or interfacing position or level sensors to data
acquisition and control systems. The high density DIN rail mounting
offers an extremely compact solution for saving valuable panel space.

Configuration

In a valve positioning application a potentiometer is sometimes used
as a feedback signal. Quite often a wide open valve is only a 25% turn
of the feedback potentiometer. The Q438 can easily be adjusted with
the zero and span to provide a fullscale output signal (e.g. 4-20mA)
representing 0-25% or even 50-75% of the potentiometer input.

 High Density DIN Rail Mounting
 Flexible DC Power Supply 9 to 30VDC
 SnapLoc

2. Connect the input to a potentiometer. Connect the output to
the actual device load (or a load approximately equivalent to the
actual device load value) and apply power.

Note: To maximize thermal stability, final calibration should be
performed in the operating installation, allowing approximately 1
to 2 hours for warm up and thermal equilibrium of the system.

3. Set the input to the desired minimum and adjust the zero
potentiometer for the desired minimum output.

4. Set the input to the desired maximum and adjust the span
potentiometer for the desired maximum output.

5. Repeat steps 3 and 4, if necessary.

TM

Plug-in Terminals

Table 1: Input Range Settings

Unless otherwise specified, the factory presets the Model Q438 as
follows:

Input Range:

0 to 100%

Output: 4 to 20mA

For other output ranges, refer to Tables 1 and 2 to reconfigure
switches SW1 and SW2 for the desired input and output ranges.

WARNING: Do not change switch settings with power applied.
Severe damage will result!

Calibration

Note: For best results, calibration should be performed with the
intended output load, in the operating environment, mounted on
a DIN rail, allowing at least one hour for thermal equilibrium of the
system.

. With power disconnected, set the output and input switch

1
selectors (SW1 and SW2) to the desired ranges (see Tables 1 and 2).

Table 2: Output Range Settings

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Specifications

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Potentiometer Input:

End-to-end Resistance: 100 ohms up to 100k ohms
Input Impedance: >1M ohms
Input Excitation: 500mV, 5mA maximum drive.
Zero Turn-Up: 80% of full scale input
Span Turn-Down: 80% of full scale input

Output:

Voltage:

Output: 0-5V, 0-10V
Source Impedance: <10 ohms
Drive: 10mA, max. (1k ohms min. @10V)

Current Output:

Output: 0-1mA, 0-20mA, 4-20mA
Source Impedance: >100k ohms
Compliance:

0-1mA; 7.5V, max. (7.5k ohms, max.)
0-20mA; 12V, max. (600 ohms, max.)

4-20mA; 12V, max. (600 ohms, max.)

Accuracy (Including Linearity, Hysteresis):

±0.1% maximum at 25°C

Stability:

<±0.05%/°C maximum of full scale range

Response Time (10 to 90%):

<200mSec., typical.

Common Mode Rejection:

120dB @ DC, >100dB @ 60Hz

Isolation:

1800VDC between line power and input, output

LED Indication (green):

Active DC power

Humidity (Non-Condensing):

Operating: 15 to 95% @ 45°C
Soak: 90% for 24 hours @ 65°C

Temperature Range:

Operating: 0 to 55°C (32 to 131°F)
Storage: -25 to 70°C (-13 to 158°F)

Power:

Consumption: 1.5W typical, 2.5W max
Range: 9 to 30VDC

Weight:

0.48 lbs

Agency Approvals:

UL recognized per standard UL508 (File No. E99775)
CSA certified per standard C22.2 No. 0-M91

and 142-M1987 (File No. LR42272-84).

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Ordering Information

Models And Accessories
Specify:

Model: Q438-0000

1.

2.

Specify optional I/QRail, type and quantity.

3. Optional Custom Factory Calibration; specify C620 with desired

input and output range

4. Accessories: (see Accessories)

Accessories

ActionI/Q modules will mount on standard TS32 (model MD02) or TS35
(model MD03) DIN Rail. In addition, the following accessories are available:

MD02 TS32 DIN rail

MD03 TS35 x 7.5 DIN rail
IQRL-D002 2 Position I/QRail & DIN rail
IQRL-D004 4 Position I/QRail & DIN rail
IQRL-D008 8 Position I/QRail & DIN rail

WV905 24VDC Power Supply (0.5Amp)

H910 24VDC Power Supply (1Amp)
H915 24VDC Power Supply (2.3Amp)

Printed on recycled pape

Dimensions

Action Instruments

Chessell

Eurotherm