controller is a special instrument for pressure control in industrial process
measurement and control system. It is usually called pressure switch in
engineering. According to the working principle, it can be divided into the
following two categories.
to the working principle, it can be divided into the following two categories:
1. Mechanical pressure controller;
2. Electronic pressure controller
the pressure in the system is higher than a certain set pressure timing, the
free end of different pressure sensing elements (spring tube, diaphragm,
diaphragm box, bellows, piston, etc.) generates displacement, and drives the
disc in the switch to move instantaneously through the link guide rod.
the pressure drops to the rated recovery value, the disc moves in reverse
instantaneously, the switch resets automatically, and finally outputs an
electrical signal of the switching quantity.
controller: When the input pressure reaches the set value, the instrument can
control and alarm the controlled pressure through the on-off function of the
value high-switching value: When the input pressure rises, the controller
generates the pressure value when the control or alarm signal changes.
value: When the input pressure drops, the controller generates the pressure
value when the control or alarm signal changes.
gap: the difference between the switching value and the low-switching value at
the same set point.
error: The difference between the set value and the measured actual value when
the output variable is output according to the specified requirements.
range: Set point adjustable controller. The difference between the maximum
pressure value and the minimum pressure value that can be adjusted by setting
DIFF is pressure difference, which refers to poor handover. It is often called
"disconnection difference" or "dead zone" in use. It refers
to the difference between the set action value and the reset value of the
switch. For example, when the set value is 1 MPa and the actual reset value is
0.9 MPa, the interruption difference is 0.1 MPa. Each pressure switch has this
parameter, but some of the dead zones of pressure switches are adjustable, and
some of the dead zones of pressure switches are not adjustable.
debugging the pressure controller, first of all, we need to know whether the switching
value we use is the high-switching value or the low-switching value. Whether
the high-switching value of the pressure controller with adjustable switching
difference needs to meet the requirements at the same time. Simply put, when
the pressure is rising, or when the pressure is falling, or both need to be
types of controllers have switch value calibration windows and switch
difference calibration windows, but the calibration windows of such controllers
can only be used as general observation, bearing in mind that they can not be
used as the standard and basis for adjusting setting points. Therefore, the
adjustment of the pressure controller must go through qualified laboratory
adjustment. Many people feedback information, they feel that the switching
value is low or high, in the absence of a standard device, "feel" or
"look at the scale" to adjust themselves, resulting in a serious
deviation of the switching value from the required set value.