IEC 60770-2:2010 pdf – Transmitters for use in industrial-process control systems -Part 2: Methods for inspection and routine testing.
5.2.3 Load conditions Electrical instrumentation:
— voltage output signals: the minimum load value specified by the manufacturer
— current output signals: the maximum load value specified by the manufacturer Pneumatic instrumentation:
— a rigid tube 8 m long and 4 mm internal diameter connected to a 20 cm3 rigid container.
5.3 Preconditioning
For preconditioning with power applied to the transmitter, sufficient time (not less than 30 mm) should be allowed to ensure stabilization of the operating temperature of the transmitter,
5.4 Adjustments
The routine tests shall be carried out (as an acceptance test or after repair) with the adjustments for lower range value, span and damping determined by the user in consultation with the manufacturer
5.5 Tests under reference conditions
55.1 Measured error and hysteresis
The input-output characteristic under reference conditions shall be measured in one measurement cycle, traversing the full range in each direction. For this, at least five points of measurement should be evenly distributed over the range; they should include points at or near (within 10 % of span) the 0 % and 100 % values of the span.
NOTE For nstrumets witti a non-I,nea input•output reiabonshp leg. .quwe law), the test points should be cho6en 10CC tO cetain Output Vue1 equally thitflbuted over the output spwi.
Measurement procedure:
Initially, an input signal equal to the lower range value is generated and the value of the corresponding input and output signal Is noted. Then the Input signal is slowly increased to reach, without overshoot, the first test point. After an adequate stabilization period, the value of the corresponding input and output signal is noted.
The operation is repeated for all the predetermined values up to 100 % of the input span. After measurement at this point, the Input signal is slowly brought down, without overshoot, to the test value directly below 100 % of Input span, and then to all other values in turn down to 0 % of input span, thus closing the measurement cycle.
The difference between the output signal values obtained at the test points for each upscale and downscale traverse and the corresponding ideal values are recorded as the measured errors. The errors generally shall be expressed as percent of the ideal Output span. All the error values thus obtained shall be shown in a tabular form (see Table 1) and presented graphically (see Figure 1).
5.6.3 AmbIent t.mp.ratur.s
The user shall measure and report at 0 % and 100 % input signal the change in observed output signal This shall be carried out at each of the following ambient temperatures:
a) 20 C (reference);
b) maximum operating temperature specified by the manufacturer;
C) 20 C;
d) minimum operating temperature specified by the manufacturer;
e) 20 °C;
The tolerance for each test temperature should be ±2 C and the rate of change of ambient temperature should be less than I C per mlnute
Before measuring the Influence effect, sufficient time (usually 3 h) shall be allowed for stabilization of the temperature of all parts of the transmitter.
Output changes shall be reported as percentages of output span.
NOTE Thai test may be omitted only whete there ii no concern about ambient temperature ellects.
5.6.4 Over-range
Before this test, measurements of the output shall be performed at 0 % and 100 $ input values. The input shall then be increased to the maximum over-range value specified by the manufacturer. After the over-range value has been applied for 1 mm, the input shall be reduced to the nominal lower range value. After a further 5 mm have elapsed, using the same input levels as before, determine the changes in observed output values.
Differential pressure transmitters are to be tested for over-range effects in both directions. They shall be tested as described above, first over-ranging the positive chamber and then over-ranging the negative chamber. The changes in output, determined after over-ranging in each direction, shall be reported.
Output changes shall be reported as percentages of output span.
5.6.5 Static line pressure
This test shall be carried out on transmitters which in normal operation are subjected to line pressure.
Before this test, measurements of the output shall be performed at 0 % and 100 % input values. The pressure shall be changed from atmospheric to the full working pressure of the instrument. For some applications, this test may also be required to be performed at pressures below atmospheric pressure. Using the same input levels as before, the changes in observed output values shall be measured.