IEC 61514:2000 pdf download

IEC 61514:2000 pdf download.Industrial-process control systems – Methods of evaluating the performance of valve positioners with pneumatic outputs.
3.2
Input signal W
relerence input signal which represents the desired position of the associated ccntrol element
3.3
travel signal X
signal which results from the linear or angular travel caused by movement of the final control element or its actuator
3.4
output signal V
air pressure delivered to the actuator of the final control element
3.5
supply pressure P
air pressure at the supply connector of the positioner
3.6
action
action is direct when the output signal V increases as the value of the input signal W increases, The action is reverse when the output signal V decreases as the value of the input signal W increases
3.7
split ranging
special adjustment in which the full travel of the actuator is achieved from only part of the whole input range (for example 0% to 50% or 50 % to 100%)
3.8
gain characteristic
relationship between input signal Wand output signal V with travel signal X kept constant (I.e. locked stem); see figure 2
Incremental gain Y’W varies with pressure and the related pressure shall be stated.
3.9
proportional (average) gain factor K9
gain over the full range of the actuator. The proportional gain factor for a single.acting posilioner may be derived from the gain characteristic (figure 2a):
where max is the change of input signal Was a percentage of span required to change the output signal over the whole range (Vmax for 100 %). In this case Wmax (%) corresponds to the proportional band X9 (%). The output signal range Yr is taken to be the nominal range stated by the manufacturer.
For a double-acting positioner, a gain factor for each output may be derived separately (see figure 2b):
The test values shall be corrected back to the standard reference atmosphere conditions listed above. The standard reference atmosphere is equivalent to the normal reference operating conditions commonly identified by the manufacturer.
It is recognized that there may not be a factor to correct for humidity. When measurements within the recommended range of ambient conditions are unsatisfactory, and the correction factors to adjust parameters to the standard atmosphere are unknown, repeat measurements (referee measurements) may be conducted under the conditions listed in table 1, a or b, or other reference operating conditions identified by the manufacturer.
NOTE Special equipment may be required to maintain the basic test conditions within the limits specified.
4.1.1 Recommended limits of ambient conditions for test measurements
Electromagnetic field: value to be stated, if relevant.
Maximum rate of change of ambient temperature permissible during any test: 1 °C in 10 mm, but not more than 3 °C/h.
4.2 Supply conditions
4.2.1 Reference values
Electrical supply: the values specified by the manufacturer.
Pneumatic supply: the values specified by the manufacturer, or a supply pressure of 4,0 bar (400 kPa).
5 General testing procedures
5.1 Test equipment
When the accuracy rating of the reference measuring means is one-tenth or less than that of the device under test, the accuracy rating of the reference measuring means may be ignored in calculations, but shall be reported. When the accuracy rating of the reference measuring means is one-third or less, but greater than one-tenth of that of the device under test, the accuracy rating of the reference measuring means shall be stated in the report.
5.2 Test methods
Specific test methods and test configurations are described separately in clause 6.
5.3 Testing precautions
Unless affecting the influence condition being tested, the following conditions shall apply.
An adequate time, as specified by the manufacturer, shall be allowed after switching on the power supply in order to allow stabilization of the positioner and/or associated test equipment. In the absence of a manufacturer specification, a period of at least 15 mm shall be allowed (at least 30 mm for electrical supplies).
Prior to recording observations, the device under test shall be exercised by three or more full range traverses in each direction.