Why isn’t the instrument for the upper limit switch on the electric actuator modified to be an ammeter?
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This post was last edited by ZhenXunBingYi on 2020-4-17 at 14:16. The purpose of the indicator used in limit switches is to make it easy to see the position of the switch. Wouldn’t it be simpler to modify an ammeter for this purpose? A series ammeter is all that’s needed; the magnitude of the current allows one to easily determine the position of the switch. Can anyone explain why this approach isn’t used?
The limit switch on the electric valve is usually connected to the DCS, in order to indicate whether the valve is in the closed or open position; this helps to interlock and stop the operation of the motor
To operate an ammeter, a switch signal is also required; why go to the extra effort of increasing costs and complexity?
Simply remove the limit switch and connect an ammeter in series to observe; there is a physical limit mechanism below the actuator that can also serve to achieve the purpose of limiting motion
The valve position feedback signal is a current signal.
What I mean is to replace the limit switch with an ammeter, so that the pointer of the ammeter can be used to make a judgment
Your idea is adding extra steps that aren’t necessary! The position switch has an obvious mechanical indication – so what’s the need for an ammeter? Doesn’t an ammeter cost money? Does an explosion-proof device also need to be equipped with an explosion-proof ammeter? The switches inside are two passive contact IO points. Received from the PLC or controller. What current do you want the ammeter to display?
The electrical unit has an output option with continuous valve positions, along with an additional circuit board. For angular stroke output, the source signal is taken from the internal rotary encoder. The valve position switch signal from Denso is typically obtained from a torque switch (or a position switch), and it is used to determine the starting position of the valve stem as well as to set the torque value for a \"tight close\" condition. Inside the Denso unit, there must be a valve position switch, as well as an encoder (similar to a servo level gauge, which is used to determine the position within the range of motion). The output switch is standard, while the continuous valve position is not standard.