Kipp & Zonen CT24 User manual

Kipp
Zonen
&
0305 360
24
SIGNAL AMPLIFIER 4 20 mA
INSTRUCTION MANUAL

1
INSTRUCTION MANUAL CT 24
IMPORTANT USER INFORMATION
Reading this entire manual is recommended for full
understanding of the use of this product
The exclamation mark within an equilateral triangle is intended to
alert the user to the presence of important operating and
maintenance instructions in the literature accompanying the
instrument.
Should you have any comments on the product or this manual we
will be pleased to receive them at:
Kipp & Zonen B.V.
Röntgenweg 1 2624 BD Delft Holland
P.O. Box 507 2600 AM Delft Holland
Phone [phone]
Fax [phone]
E-mail [email protected]
Kipp & Zonen reserve the right to make changes in the
specifications without prior notice.
IMPORTANT USER INFORMATION

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INSTRUCTION MANUAL CT 24
WARRANTY AND LIABILITY
Kipp & Zonen guarantees that the product delivered has been
thoroughly tested to ensure that it meets its published specifications.
The warranty included in the conditions of delivery is valid only if the
product has been installed and used according to the instructions
supplied by Kipp & Zonen.
User made modifications can affect the validity of the CE
declaration.
Kipp & Zonen shall in no event be liable for incidental or
consequential damages, including without limitation, lost profits, loss
of income, loss of business opportunities, loss of use and other
related exposures, however caused, arising from the faulty and
incorrect use of the product.
COPYRIGHT
©
2003KIPP & ZONEN
All rights reserved. No part of this publication may be reproduced,
stored in a retrieval system or transmitted in any form or by any
means, without permission in written form from the company.
IMPORTANT USER INFORMATION

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INSTRUCTION MANUAL CT 24
Declaration of Conformity
According to EC guideline 89/336/EEC 73/23/EEC
We Kipp & Zonen B.V.
Röntgenweg 1
2624 BD Delft
Declare under our sole responsibility that the product
Type: CT 24
Name: Solar Sensor Amplifier 4 – 20 mA
To which this declaration relates is in conformity with the following
standards:
Imissions EN 50082-1 Group standard
IEC 1000-4-2
IEC 1000-4-3
IEC 1000-4-4
Emissions EN 50081-1 Group standard
EN 55022
Safety standard IEC 1010-1
Following the provisions of the directive
CE DECLARATION OF CONFORMITY
B.A.H. Dieterink
President
KIPP & ZONEN B.V.

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INSTRUCTION MANUAL CT 24

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INSTRUCTION MANUAL CT 24
TABLE OF CONTENTS
WARRANTY AND LIABILITY 2
Declaration of Conformity 3
1. GENERAL INFORMATION 7
2. SPECIFICATIONS 9
3. CONNECTION OF THE CT 24 11
3.1 Minimising interference 12
3.2 Selecting the supply voltage 13
3.3 Connection for current output 13
4. NEGATIVE INPUT SIGNALS 17
5. CALIBRATION PROCEDURE 19
5.1 Standard calibration 19
5.2 Special calibration. 20

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INSTRUCTION MANUAL CT 24

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INSTRUCTION MANUAL CT 24
1. GENERAL INFORMATION
With the CT 24 it is possible to convert a low level voltage output
from a solar sensor to the standard level of 4 – 20 mA or (using the
supplied 500 Ohm resistor) to a 2 – 10 Volt signal.
The CT 24 amplifier is designed to use with Kipp & Zonen solar
sensors, to allow long cables between sensor and data logger
without external interference.
The large operation temperature range from - 30°C to + 70°C and
the waterproof housing (IP 65) makes that the CT 24 can be used
under the same conditions as all solar sensors.
The amplification can be adjusted from the standard 0 – 20 mV is
4 – 20 mA to a value that takes the calibration factor of the sensor
into account, like 0 – 1000 W/m² is 4 – 20 mA.
Even negative inputs are allowed through a positive shift of the zero
point from +4 to + 8 mA.
This allows for negative input signals of about 250 W/m² like a
pyrgeometer produces.
The CT 24 is protected against reversed polarity, voltage surges on
input and output lines and is shielded against EMF disturbance.
For pyranometers with temperature sensors there are special
connector strips in the CT 24 to connect these sensors from in going
to out-going cable.
GENERAL INFORMATION

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INSTRUCTION MANUAL CT 24

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INSTRUCTION MANUAL CT 24
2. SPECIFICATIONS
Power supply @ R L d125 :+12 to +30 VDC
Input range -5 to +20 mV
Gain adjust +0.5 to +1.0 mA / mV
Zero adjust +3 to +8 mA
Temperature range (operating) -30°C to +70°C
Housing Aluminium, grey lacquered
Dimensions W x D x H 64 x 58 x 34 mm
Water proof IP 65 / DIN 40050
Cable glands size 4 to 6,5 mm
Voltage output +2 to +10 V
SPECIFICATIONS

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INSTRUCTION MANUAL CT 24

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INSTRUCTION MANUAL CT 24
3. CONNECTION OF THE CT 24
The CT 24 is meant to boost the (low level) output signal of a solar
sensor. Therefore the CT 24 amplifier needs to be close to the
sensor to maintain a high signal to noise ratio in the cable.
The internal layout of the CT 24 is shown in figure 3.1.
figure 3.1 Internal layout of the CT 24
To prevent errors due to current loops between input
and output it is necessary that the sensor outputs
are floating (not connected to ground) or that the ( )
from the power supply is not connected to ground.
In case of doubt check the impedance of the sensor wires
against the sensor housing, this should be infinite.
CONNECTION OF THE CT 24
OUTPUTINPUT
GND
GNDZERO ADJUST
GAIN ADJUST

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INSTRUCTION MANUAL CT 24
3.1 Minimising interference
To obtain maximum signal to noise ratio both before and after the
CT 24, it is advised to connect the CT 24 as described in this
chapter.
All Kipp & Zonen sensor cables have an internal shield that has to
be connected to the ground (housing) of the CT 24. For this
purpose pin 1 of the input connector strips can be used or one of
the screws that holds the PC board in place. Also the outgoing
cable must have an internal shield connected to the ground inside
the CT 24. For this purpose pin 1 of the output connector strips can
be used or one of the screws that holds the PC board in place.
If you don’t want to connect the cable shields to the housing but
only interconnect with each other, use one of the interconnections
instead of pin 1. Make sure that the cable diameter is within the
size that the cable glands can hold (4 – 6.5 mm)
SHIELD 1 1 SHIELD
SIGNAL INPUT 2 2 SIGNAL OUTPUT
SIGNAL + INPUT 3 3 SIGNAL + OUTPUT
INTERCONNECTION 4 4 INTERCONNECTION
INTERCONNECTION 5 5 INTERCONNECTION
INTERCONNECTION 6 6 INTERCONNECTION
INTERCONNECTION 7 7 INTERCONNECTION
INTERCONNECTION 8 8 INTERCONNECTION
INTERCONNECTION 9 9 INTERCONNECTION
figure 3.2 internal connection strip
CONNECTION OF THE CT 24

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INSTRUCTION MANUAL CT 24
3.2 Selecting the supply voltage
The CT 24 operates as a so-called 2 wire current transmitter. This
means that the amplifier receives its operating current from the
loop that represents the current output signal.
The loop has to be powered with a power supply capable of
providing a voltage between 12 and 30 Volt @ 125 Ohm. When
later on the current is to be transformed to a voltage, it is important
to select the power supply voltage in accordance with the desired
output voltage.
Example:
Required voltage over the CT 24 is 9 Volt (minimum value)
Required voltage over the 500 Ohm resistor is 10 Volt (@ 20 mA)
This implies that the supplied voltage has to be at least
9+10 = 19 Volt.
3.3 Connection for current output
When the CT 24 is used as a standard 420 mA amplifier
(transmitter) only 2 input and 2 output wires have to be connected
plus two times the shielding of both cables.
The cable coming from the sensor is lead through the cable gland
and directly connected to pin 2 (-) and 3 (+) of the input connector
strip.
Check your sensor manual for the colour of the wires.
The outgoing cable has the same number of wires as the input
cable and can be connected to the output strip. Make sure both
cables have their shield connected to ground.
CONNECTION OF THE CT 24CONNECTION OF THE CT 24

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INSTRUCTION MANUAL CT 24
Input connector pins number 4 till 9 are interconnected with the
output connector pins and can be used to transfer the signal from
temperature sensors like a Pt100 or thermistor to the output cable.
figure 5.3 connection for current output
Shield
Signal +
Signal -

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INSTRUCTION MANUAL CT 24
3.4 Connection for voltage output
When a voltage signal is needed directly from the CT 24, the
conversion from current to voltage can be made inside the CT 24.
For this purpose a precision 500 Ohm resistor is supplied that can
be connected through the connection strip.
The wires used to supply the current and the wires that carry the
voltage output can not be combined. Even though the return from
the current loop and the low of the voltage output are connected to
the same level, the voltage drop over the cable makes it necessary
to use separate wires for the voltage output.
figure 3.4 voltage output connection
Power supply +
Signal +
Signal –
Power supply –
Shield

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INSTRUCTION MANUAL CT 24
So when the CT 24 is used with a voltage output, 2 input and 4
output wires have to be connected plus two times the shielding of
both cables.
Of course any other R
L
can be used to transform the output
current to a voltage, as long as the guideline from chapter 5 is
followed.

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INSTRUCTION MANUAL CT 24
4. NEGATIVE INPUT SIGNALS
When using a pyrgeometer as input, the signal can be both
positive and negative. To allow for negative inputs the zero point
from the CT 24 can be adjusted to + 8mA. (see fig 3.1 zero adjust)
Example with a CG 1:
Sensor output –250 to + 250 W/m
2
= -3.750 mV to + 3.750 mV
Gain is set to 1 mA / mV
Output range is 3.75 x 2 = 7.5 mA
To see both negative and positive signals on the output the zero
has to be shifted +4 mA (3.75 minimal) to +8 mA.
See the next chapter for the calibration procedure.
NEGATIVE INPUT SIGNALS

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INSTRUCTION MANUAL CT 24

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INSTRUCTION MANUAL CT 24
5. CALIBRATION PROCEDURE
Calibration can be performed in two ways, either the CT 24 is
calibrated standard with an amplification of 1mA per 1 mV and no
offset adjusted (see chapter 5.1)
Or a special calibration is made where the amplification and / or
offset are adapted to the sensor (see chapter 5.2).
Necessary equipment for calibration:
-accurate voltage source
-power supply ( +12 to +30 Volt)
-accurate multimeter ( current and voltage)
-small screwdriver to adjust the potentiometers
-Resistor (R
S
) equal to the sensor element impedance
5.1 Standard calibration
To perform a standard calibration, connect R
S
in the CT 24 to the
input terminal strip pin 2 and 3. The power supply has to be
connected to the output pins 2 and 3.
Measure the loop current with the multimeter on mA range.
In this situation a zero input is simulated and the zero output can
be adjusted to +4 mA with the zero adjust potentiometer.
Then a +16 mV signal has to be applied to the input. With the gain
potentiometer the output is adjusted to +20 mA.
This gives a maximum full-scale input of +16 mV.
C
ALIBRATI
O
N PR
OC
ED
U
RE