Minimum Current Setting (Imin)
Teaching the controller the current at which the valve passes its deadband and starts delivering flow. It is generally a value between twenty and forty percent of nominal solenoid current and varies somewhat between valve types, and even between different samples of the same type.
The setting is made with the machine unloaded and the fluid at operating temperature. Current is raised in small steps starting from the lowest value; the value read at the moment the cylinder first moves is the minimum current. A value slightly below that is chosen so there is no unintended motion in neutral.
- If you measure with cold fluid you will find a higher threshold than the real one; once the system warms up, the machine jumps on the first command.
- It must be measured separately for the forward and reverse directions; spool overlap may not be symmetric on the two sides.
- It is separate for each section: the thresholds of the boom, arm, and bucket sections can come out different from one another.
Incorrect tuning has two classic symptoms. If the threshold is too low, the first part of lever travel is still wasted and motion starts late. If the threshold is too high, the load lurches as soon as the lever moves slightly. The sign of correct tuning is that a very slow but uninterrupted motion starts within the first millimeter of lever travel.
Where this term is used: What Is a Hydraulic Lever Retrofit Kit? Definition, Components, Operating Principle