WIKA T91.20 Analogue Temperature Transmitter Instruction Manual
- September 3, 2022
- WIKA
Table of Contents
WIKA T91.20 Analogue Temperature Transmitter
Intended use
The model T91.10 / T91.20 temperature transmitter is a universal transmitter,
configurable via a PC, for use with resistance thermometers and
potentiometers. The instrument has been designed and built solely for the
intended use
described here, and may only be used accordingly. The technical specifications
contained in these operating instructions must be observed. Improper handling
or operation of the instrument outside of its technical specifications
requires the instrument to be taken out of service immediately and inspected
by an authorised WIKA service engineer. The manufacturer shall not be liable
for claims of any type based on operation contrary to the intended use.
Safety instructions
When mounting, commissioning and operating these transmitters, it is important to observe the respective national safety precautions and regulations in effect (e.g. IEC 60364). Nonobservance of the applicable regulations may cause severe injury to persons or damage to equipment. Only staff with suitable qualifications should work with these transmitters. Before commissioning, check the instrument‘s suitability for the intended application. In particular, it is important to observe the ambient and operating limits as specified in the chapter 9 “Specifications”.
Mounting
Model T91.10 head mounting transmitters are designed to be mounted on a measuring insert in a DIN Form B connection head. Model T91.20 head mounting transmitters are designed to be mounted on a measuring insert in a Form J connection head. The connecting wires of the measuring insert must be approx. 50 mm [1.97 in] long and insulated.
Maintenance
The temperature transmitters described here are maintenance free! The electronics do not incorporate any components which could be repaired or replaced. Depending upon operating conditions, it may be advisable to check the calibration of the transmitter yearly.
Electrical connections
These transmitters have an internal galvanic connection between the sensor input and analogue output. No external connection should be made (for example, by earthing) between the connected temperature sensor and analogue output! For this reason it is best to use isolated thermocouples. For flying leads we recommend using crimped connector sleeves. To connect a thermocouple: Make sure that the thermocouple is connected with the correct polarity. If the cable between the thermocouple and the transmitter must be extended, only use the appropriate thermal or compensating cable for the connected thermocouple type.
Sensor input Pt100
Model T91.10.104
Pt100 in 2- or 3-wire connection. For a 2-wire connection the resistance of the wires affects the measurement results. Therefore this circuit should only be selected if the wires are short, or accuracy requirements are low. If using a 2-wire connection, always connect a jumper between input terminals 5 and 6. Transmitter output signal: 0 … 10 V / 3-wire technology
Model T91.10.424
Pt100 in 2-wire connection Transmitter output signal: 0 … 10 V / 3-wire
technology
Model T91.20.143
Pt100 in 2-wire connection Transmitter output signal: 4 … 20 mA / 2-wire
technology
Sensor input thermocouple
Model T91.10.102
The positive lead of the thermocouple is connected to terminal TC+ on the transmitter and the negative lead to terminal TC-. Transmitter output signal: 0 … 10 V / 3-wire technology
Model T91.20.141
The positive lead of the thermocouple is connected to terminal TC+ on the
transmitter and the negative lead to terminal TC-. Transmitter output signal:
4 … 20 mA / 2-wire technology
Electrical connection 0 … 10 V output signal
Electrical connection 4 … 20 mA loop
Maximum power supply: DC 10 … 35 V (reverse-polarity protected) In the current loop the transmitter and the indicator/processor are connected in series. The transmitter regulates the current in proportion to the input signal. The load can be connected either to the positive or negative terminals of the transmitter. With the load connected to the positive terminal, the power supply and load may not have a common earth.
Transmitter adjustment
Zero point and Span adjustment is carried out via potentiometers. These are on the upper face of the transmitter. The potentiometers are protected against accidental alteration. The zero-point potentiometer can be adjusted to make small corrections. After any adjustment of the span potentiometer, a complete adjustment of the transmitter is necessary
Preparing the adjustment
Connect a suitable simulation source to the input of the T91 (Pt100 or
thermocouple simulator). When simulating a Pt100, connect the simulator in a
2- or 3-wire configuration. We recommend the use of passive resistances. When
simulating a thermocouple, the actual terminal temperature of the transmitter
must be pre-set on the simulator (cold junction compensation)
- Connect a mA meter in the 4 … 20 mA-loop or a multimeter to the 0 … 10 V output signal
- Connect a suitable power supply to the transmitter
Adjustment of the 0 … 10 V output signal
-
Set the simulator with approx. 1 V offset from the lower limit of the measuring range (e.g. -20 °C [-4 °F] = 1 V for measurement range -30 … +70 °C [-22 … +158 °F])
Turn the zero potentiometer Z, until the output signal (in our example -20 °C [-4 °F] = 1 V output signal) matches the desired value -
Set the end value of the measurement range with the simulator, e.g. +70 °C [+158 °F] for measurement range -30 … +70 °C [-22 … +158 °F]
-
Turn the span potentiometer S, until the output signal (in our example 70 °C [+158 °F] = 10 V) matches the desired value.
-
Repeat step 1 and check signal (1 V)
-
Repeat step 3 and check signal (10 V)
Adjustment of the 4 … 20 mA output signal
- Set the lower value of the measurement range with the simulator, e.g. -30 °C [-22 °F] for measurement range -30 … +50 °C [-22 … +122 °F]
- Turn the zero potentiometer Z , until the output signal shows the desired value
- Set the end value of the measurement range with the simulator, e.g. +50 °C [+122 °F] for measurement range -30 … +50 °C [-22 … +122 °F]
- Turn the span potentiometer S, until the output signal shows the desired value
- Repeat step 1 and check output signal of zero point
- Repeat step 3 and check output signal of span
Closing steps
Disconnect the simulator, the multimeter and the power supply
Faults
When measuring with resistance thermometers or thermocouples, factors arising
from the design and measuring technology used can falsify the results
measured. The most important effects that can lead to faults are listed below:
Disposal
Incorrect disposal can put the environment at risk. Dispose of instrument components and packaging materials in an environmentally compatible way and in accordance with the country-specific waste disposal regulations. Do not dispose of with household waste. Ensure a proper disposal in accordance with national regulations.