Pressure controller use and adjustment
Pressure controller use and adjustment
Many pressure controllers are used in the refrigeration system, and the pressure is controlled by the on and off of the contacts. Mainly include high pressure pressure controller, low pressure pressure controller, high and low pressure pressure controller, pressure difference controller and oil pressure protection pressure controller. The operating principle of the pressure controller is basically the same, which is detected by the pressure detection mechanism and controlled by the actuator. The bellows undergoes expansion and contraction deformation after being compressed, which drives the swing rod to move, and then through the swing rod to switch the contacts on and off, the pressure is controlled.
Two parameters of DIFF and RANGE are often seen on the pressure controller. RANGE is the pressure range, DIFF is the pressure difference, which refers to the switching difference, which is the dead zone, which is a switching area.
Each pressure switch has this parameter, and the switching difference of the controller is adjustable or non-adjustable according to different requirements. Adjustable is called adjustable set point, otherwise it is not adjustable set point. For example, the fixed working pressure difference of Jy616 pressure controller is 0.5～1kgf/cm2, this kind of pressure difference is fixed within a certain range.
High pressure pressure controller and low pressure pressure controller
(1) Principle of action: The working principle of the high pressure pressure controller and the low pressure pressure controller are the same. When the pressure in the bellows rises and its value is higher than the setting value of the main adjusting spring, the bellows will stretch or shorten (the bellows is compressed for external pressure type to shorten, and internal pressure type is extended), push the pendulum rod, and toggle Contact, cut off the power supply, play a high-voltage protection role. If the power is cut off when the pressure is too low, it will play a role of low pressure protection. Take the high pressure pressure controller as an example to introduce the control pressure range. When the pressure is P1, the contact is on, when the pressure is P, the contact is broken, and the working pressure difference range is P～P1.
When the pressure is high, the contact is broken, when the pressure drops to P1, the contact is on. When the pressure rises to point P, the contact opens again. The action of the low pressure pressure controller is the opposite.
(2) Working pressure difference: Working pressure difference refers to the working pressure interval between on and off of contacts. If the high-pressure controller cut-off pressure is set to 14kg, and the working pressure difference is set to 2kg, that is, when the pressure exceeds 14kg, the controller is off; when the pressure is lower than 12kg, the controller is on. Reduce the working pressure difference and improve the control accuracy. But it cannot be adjusted too small, otherwise it will move frequently. The controller's contact action should be flexible, and it must be turned on and off instantly, otherwise it will cause spark discharge and burn the contact.
(3)Structure and adjustment: When the pressure of the input bellows increases, the bottom plate of the bellows moves (the amount of movement is determined by the difference between the pressure and the spring force), driving the swing lever and controlling the contact action. When you need to adjust the pressure control range, turn the pressure adjustment screw counterclockwise/clockwise, and adjust the pressure set by yourself with a multimeter.
