What is a pressure switch?
In a hydraulic elevator, the pressure switch is a device containing an electrical contact that closes or opens depending on the pressure reading it receives from the fluid. This pressure is generated by the weight of the cabin and the load through the fluid on the valve group.
(1) NO overload pressure switch (regulation screw at the base of the pressure switch in green).
The new ITC for elevators requires regulating the load of the elevator to avoid accidents related to it.
How a pressure switch works
Inside the pressure switch, the fluid exerts pressure, such that it moves a small internal piston that connects two contacts. When the pressure drops, a spring pushes the piston in the opposite direction and the contacts separate. The adjustment screw (1) allows the pressure level at which the pressure switch starts to operate to be adjusted. If the screw is tightened, the trigger pressure increases; if it is loosened, the pressure decreases.
A pressure switch does not measure pressure, for this function GMV has so-called pressure transducers.
Types of pressure switches
GMV has four types of pressure switches, which can be incorporated as accessories or spare parts in all mechanical valve groups model 3010.
- Overload pressure switch: used so that, in the event that the weight of the cabin is greater than the nominal load, the control panel gives an excess load warning. It allows users to reduce the weight in the cabin for optimal elevator operation. It can be supplied with a normally open (NO) or closed (NC) contact and reaches pressure values from 5 to 50 bar.
- Maximum pressure switch: If the pressure rises above the maximum value, the safety valve of the valve group (VS) is activated. Through the maximum pressure switch, the control panel receives a signal that the pressure has risen above the safety level and this stops the lift. It can be regulated from 10 to 100 bar. It has two contacts, one NO and one NC.
- Minimum pressure switch: Allows regulation at very low pressures, from 1 to 12 bar. Its function is to warn the control panel that the circuit pressure is below the minimum pressure (usually 5 bar). The minimum pressure switch warns, for example, of a hose breakage or the triggering of the parachute valve.
GMV, as a manufacturer of hydraulic groups, recommends and promotes the use of pressure switches as a tool through which the operator can have information on the status of the cabin in real time.
Related posts:
Regulation of the GMV pressure switch to comply with section 5.12.1.2 of regulation N.81.20
2 comments
Very interesting information about pressure switches, although it is information that only those of us who are familiar with the subject of elevators know, it is quite useful that you share it so that general knowledge about elevators is spread and a community is generated around it, thanks for the information.
Hello, how does the oil temperature affect the regulation of the pressure switch when it is used as a weighbridge? Thanks and regards.