Frequently Asked Questions
An RTD (Resistive Temperature Device) is a sensor that changes resistance with temperature in a linear relationship. RTDs are the most common temperature sensors used with rotary temperature transmitters. They may be specified as PT-100 indicating platinum-tungsten with a resistance of 100 ohms at 0° C, PT-200, or PT-2000 and typically have a temperature coefficient of a = 0.00385.
A rotary temperature transmitter communicates a temperature sensor signal from a rotating godet (draw roll) to a stationary process control system that regulates the heater under the godet.
A rotating sensor senses the temperature of the godet roll shell directly under the yarn wrap, exactly where the temperature must be controlled. A stationary sensor measures the temperature in an air gap near the base of the godet, far from the yarn wrap, introducing errors that vary with distance from yarn wrap, location of sensor in air gap, roll speed, ambient air temperature and humidity and desired process control temperature. A stationary sensor can be "tuned in" manually, but as soon as there is a change in any of the parameters listed above it will drift out of calibration.
A thermocouple is another type of temperature sensor in which two wires of different metals (e.g. Iron and Constantine) are connected together at the point of temperature measurement (hot junction) and connected at the other end in an ambient temperature location (cold or reference junction). The dissimilar metals generate a low level current from the hot junction to the cold junction that is sensed. Although these devices are very simple and robust, they are not linear and the requirement for a cold reference junction means they are typically not suitable for rotary temperature use.
Not easily. To accommodate a rotating sensor and rotary temperature transmitter the godet needs to be modified to accept an RTD in the wall of the roll shell under the yarn wrap, the roll motor shaft needs to be gun drilled through to allow the RTD lead wires to exit out of the back of the roll motor and the rotary transmitter needs to be fitted to the rear motor shaft.
A key advantage to digital measurement is that you only measure once - at the sensor. The measurement is immediately converted to a digital "word" for further processing (e.g. transmitting from the rotating transmitter to the stationary pickup) so it's a fixed value that can't be altered in the process. In contrast, an analog measurement is re-measured at each step in the process (e.g. it may be converted to a frequency to send from the rotating transmitter to the stationary pickup and that frequency must be accurately re-measured on the stationary side). Each time it is re-measured, the opportunity for error is introduced.
The TempTrak transmitter uses a tuned resonant inductive coupling, which allows the power and data to transmit over a greater gap. It also allows a generous +/- 3 mm adjustment tolerance, which eliminates any critical positioning during installation. In addition, because the TempTrak system sends digital language across the gap, it is able to constantly monitor and optimize the power level of the rotor, which would otherwise vary with the transmitter spacing. ^
Poor godet temperature control can have a negative affect on yarn quality. Yarn color is a primary concern, whether the color is introduced in the extruder or later in a dyeing process. An off-color thread line in a solid color weave will appear as streaking. Mechanical properties of the yarn including tenacity (stiffness), emissivity (how light reflects) and strength are also affected by godet roll temperature.
Elevated temperatures can shorten the life of electronic components. Locating the stationary circuit away from the hot harsh roll motor environment helps achieve the outstanding reliability of the TempTrak transmitter. The simple DIN-rail controller interface takes up minimal room and typically fits in an existing cabinet where it is immediately accessible to evaluate any error codes - codes that direct the operator to problems in the temperature control system that are quickly remedied (e.g. failed sensor) without having to pull the motor assembly for troubleshooting.
The transmitter on the back of the godet roll motor assembly is connected to the Controller Interface by a coax cable. The maximum recommended length of this cable is 30 meters (100 feet). This is typically more than enough length to remove the controller interface from the harsh motor environment.
The TempTrak Transmitter's flexible mounting style allows it to fit most machines. Mechanical configurations for Rieter, Neumag, Barmag, Erdmann, Toray, Plantex, G.E., Fycon, PASCO, ISGEV and others are available. If your roll motor does not meet one of these existing designs, Binsfeld will create a mechanical configuration to suit your needs. A design configuration fee is charged for this service, but is waived if 10 or more systems are ordered.
Yes, the TempTrak design allows for shafts up to 30 mm to pass through the rotating transmitter and stationary pickup. This allows it to be used in applications where there is an outboard sheave (e.g. belt driven godet) or where the transmitter must be located between the motor and the roll assembly.
Yes. If you provide the temperature table or curve for your non-standard sensor, Binsfeld can program the transmitter to work with it.