First of all, the life of the solenoid coil is determined by the quality of the coil itself, but in terms of the actual use of the coil, it is also affected by many application factors. Specifically, there are the following factors that may cause adverse effects on the coil life:
1. Temperature: After a certain period of time the coil system is warmed –up and reaches a final operational temperature. This period of time may differ, depending on solenoid construction, voltage variation, ambient temperature, valve size and piping system, If the temperature is too high for a long time, its service life will be affected
2. Improper use: during the use of the solenoid coil, improper selection of the voltage, current, power, etc., such as too much voltage or current supplied by the power supply, etc., will also have a certain adverse impact on the life of the solenoid coil
3. Use environment: if the electromagnetic coil is used in wet and humid environment for a long time, water vapor is easy to enter the coil and cause short circuit, which will seriously affect its service life
Encapsulation: It is used to combine coil parts into a whole, which plays a role of waterproof and dustproof. The plastic covered materials include thermosetting plastics and thermoplastic plastics.
Thermoplastic: this kind of plastic is characterized by being soft with the increase of temperature, being molded and hard after cooling. This process can be repeated many times. The thermoplastic coil has good weather resistance and toughness. The most common material is PA66, followed by PA6.
Thermosetting plastic: this kind of plastic is characterized by curing at a certain temperature, after a certain time of heating or adding curing agent. The solidified plastic is hard and insoluble in the solvent, and cannot be softened by heating. If the temperature is too high, it will decompose. The thermosetting coil has high temperature resistance, small shrinkage and flat shape during injection molding. At present, all the thermosetting materials are BMC, but the content and formula of glass fiber are slightly different.
Beris Coils are designed and tested for continuous service. They all meet the thermal endurance specifications according to IEC 216.
Coil’s own temperature rise due to energisation.
Including effect of fluid temperature at catalogue rated limits (Electrical characteristics, solenoid operator’s ambient temperature range)
The standard coils are available for insulation classes E , F and H. The insulation class determines the coil’s maximum operating temperature for a specific life:
- Class H: 30 000 hours
- Class F: 20 000 hours
The temperature rise of continuously energized coils depends on size and power consumption. This, in turn, determines the maximum differential pressure rating of a valve as indicated in the catalogue.
An example for insulation class F, the insulation is designed for the coil to be operated at temperatures in accordance with class F, i.e. 155℃.The max. temperature rise of the coil when energized is limited, depending on the type of coil(e.g.80 ℃(FT),95℃,105℃(FB),130℃(FF)).
According to the type of coil used, the solenoid operator’s maximum ambient temperature (given under “Electrical characteristics” in the specific catalogue pages) including fluid temperature effects may be 75,60,50, or 25℃.
Determining factors may be either:
a) Temperature considerations (own temperature rise)
b) Power considerations
c) Higher temperature rise, as result of increased wattage (required for valve pressure ratings).
d) Ambient and /or fluid temperature
There are two solenoid valve categories: The first category with identical AC and DC design offers easy adaption of the same valve to AC or DC; full interchangeability is ensured for alternating or direct current.
AC Solenoids are always equipped with a shading coil in the plugnut (stationary core) and the top of the core is flat faced and perpendicular.
AC/DC Solenoid comparison
AC service
a) High inrush and low holding current
b) High pull force
c) Sensitive to dirt
d) The coils have less windings(copper) than DC coils
e) Power consumption and pull force not sensitive to temperatures.
DC service
a) Inrush current equals to holding current
b) Power consumption and pull force depend on temperature
c) Solenoid operates quietly
d) Not sensitive to dirt
e) The coils have more windings (copper) than AC coils
Power consumption for AC:
With:
PA = inrush VA value
PM = holding VA value
Power consumption for DC
P(W) = U.I
I(A) = P(w)/U(V)
