Why does a solenoid fail

Heat accelerates unwanted chemical reactions. Reduce oil temperature with a heat exchanger. Environmental Conditions Abnormally high or abnormally low ambient temperatures to which a solenoid is exposed for an extended time may cause a solenoid to burn out.

Dead End Service Fluid circulating through a solenoid valve helps to carry away electrical heat. Some valves depend on fluid flow to keep excessive heat from accumulating, and if used on dead end service, where the solenoid remains energized for long periods without fluid flow, the coil may burn out from this effect, possibly in combination with other problems.

Atmospheric Moisture High humidity, coupled with frequently changing ambient temperature, may form corrosion on metal parts of the solenoid structure, causing the armature to drag or the spool to stick.

Humidity also tends to deteriorate standard solenoid coils, causing shorts in the winding. Change to molded coils or oil immersed solenoids. Keep solenoid protective covers tightly in place, and perhaps seal the electrical conduit openings after the wiring is installed. Excessive Flow Through Valve Pressure drop through the spool of a direct-acting solenoid valve caused by the flow of fluid, creates a force unbalance tending to cause the spool to move in an axial direction.

This phenomenon is described in Design Data Sheet In circuit design, be very careful not to overload such a valve above manufacturers flow rating. It should be de-rated when used with fluids of high viscosity, or fluids having a high specific gravity fire resistant fluids, etc. Checklist for DC Solenoid Valves AC solenoid valves are far more common for in-plant industrial applications, but DC solenoids may in some cases offer a specific advantage.

AC current may be run through a full-wave rectifier to obtain a DC supply. A filter capacitor may have to be added to eliminate chatter or hum. A capacitor wired across the switch contacts on AC or DC solenoids will help absorb the released energy. The best value of capacitance can be determined by trial, either by observing the intensity of the arc, or by measuring the voltage spike with an oscilloscope as various capacitors are tried.

To reduce switch arcing, a capacitor may be wired across the contacts, or a diode may be wired across the coil. Download Data Sheet. Excessive voltage causes excessive coil current which overheats the coil.

Voltage Too Low. Low voltage reduces the mechanical force of the solenoid. It may continue to draw inrush current without being able to pull in. Operation of a 60 Hz coil on 50 Hz causes the coil to draw above normal current.

Operation of a 50 Hz coil on 60 Hz causes the coil to draw less than rated current and it may burn out from inability to pull in. An induced ambient temperature above the rating will degrade the insulation between the winding, and cause shorts. Rapidly cycling a solenoid on and off keeps it from dissipating heat caused by inrush current. Inrush current occurs during initial energizing and draws current up to five times the rating as the coil is pulled in.

This can also be seen for extended periods of time if there are issues keeping the valve from shifting completely. However you slice it, if you are keeping the temperature at extremes, you will see premature failure.

Contamination by sea water was the cause of failure in the solenoid pictured at the top of this post. If the operating fluid becomes contaminated, that can lodge in the spool and body, or cause rust to form. When this happens, a high current condition can become extended, which will cause overheating and failure.

Contamination can also cause a valve to fail to shift completely, which would hold both coils on a double solenoid valve as energized simultaneously. In this case, the first energized coil will fight the second coil, causing current to rise.

These are just a few common reasons you can find if you are suffering from solenoid burnout. We can investigate for these, or any other issues causing part failure, and find solutions that can save you money and reduce downtime. Spot on Scotty! Nice reminder about the proper operating conditions to ensure longevity of solenoid valves.

Too high, and the orifice opens but not fully. Other causes are a broken or bent valve seat , incorrect installation or a missing solenoid valve component. This can help you to pinpoint the cause fast and more accurately. A partially closing valve can be the result of pressure difference , bad valve seats , or damaged solenoid tube. It usually happens when the plunger cannot displace the seal to the required position for a total shut off. A high pressure solenoid valve, for example, would fail to close fully if the system pressure levels are too low.

This usually occurs in water or air actuated solenoid valves, that feature a pilot orifice to amplify the closing force. A partially closed solenoid valve will also result from residual magnetism in the coil windings. Both scenarios can be disastrous and call for immediate action , especially if the solenoid valve is used in a manufacturing or testing system. Finding out the reason for the partial closure is the first step to finding the solution. In most cases, the problem can be remedied easily.

The coil windings in a solenoid valve are prone to the effects of a short circuit, wrong voltage, and extreme temperatures. The coil may melt or burn, affecting the operation of the valve. Apart from media temperatures and over-voltage , a solenoid valve coil will also burn due to a slow or bent armature.

This problem can be prevented by observing a few things, both during valve selection and after installation. These are usually made from materials that can withstand heat extremes, such as steel or brass. A faulty solenoid valve may produce erratic sounds during operation.

The type of noise varies depending on the exact cause and valve design. It could be a water hammer bang , which is common with water solenoid valves, or a continuous buzz when the coil energizes. The problem can result from pressure differences across the inlet and outlet ports , or it can be due to media passing through a small pipe diameter.

Valve noise can be annoying.