What is a solenoid valve coil?
The purpose of a solenoid valve coil is to convert electrical energy into linear motion. The coil consists of copper wire (or aluminum) wound around a hollow form. When electric current flows through the coil, a magnetic field is created. This is accomplished by placing a ferromagnetic core inside the coil. In a solenoid valve, the ferromagnetic core is called the valve plunger. When the current flows through the coil, the lines of magnetic flux turn the plunger into an electromagnet. The magnetic field causes the plunger to slide further up into the coil, opening the valve body orifice or pilot orifice.
Solenoid Valve Coil Voltages
Solenoid valve coils are available for both DC and AC electricity. Although a coil can be made to work with almost any imaginable voltage, the most common voltages available are:
- 6-Volt DC
- 12-Volt DC
- 24-Volt DC
- 24-Volt AC
- 120-Volt AC
- 220/240-Volt AC
Types of Coil Construction
Solenoid valve coil construction usually falls in one of the following two categories:
- Tape Wrapped Coils
- Encapsulated (or Molded) Coils
A tape wrapped coil is manufactured by looping conductor wire (also called magnet wire) around a spool or bobbin. The magnet wire has a thin insulation layer around it. The completed winding is then protected by a insulation tape. Thus, the name tape wrapped coil.
Encapsulated coils basically follow the same basic principle as the tape wrapped coil. However, instead of being protected by tape, the winding is encapsulated or molded over in suitable resin.
Tape wrapped coils are used in applications with relatively mild environments. Tape wrapped coils allow for much smaller production runs. However, tape wrapped coils have a much lower resistance against moisture than encapsulated coils. In addition, encapsulated coils have much stronger lead wires (to protect against pull-out).
Coils with DIN Connectors
Valve manufacturers often offer a DIN connector option on their coils. Instead of lead wires, the coil will have prongs or pins to accept a standard DIN connector. The coil is considered to have a male connection and the plug connecting to the coil is a female connector. Using a DIN connector provides many advantages: quick valve or coil exchange, excellent insulation properties, possible water tightness etc.
The connector standard used for solenoid valves is DIN 43650 . The DIN 43650 series consists of five connectors, which have the following pin spacing:
- DIN 43650 Form A - 18 mm
- Industrial Form B - 11 mm
- DIN 43650 Form B - 10 mm
- DIN 43650 Form C - 8 mm
- Micro-Mini - 9.4 mm
DIN connectors can be purchased as shells to be wired by the installer or they may be factory molded with a cable assembly. They have usually contain three or four terminals or pins. Some DIN connectors are available with LED indicators which indicate the power state of the coil for diagnostics purposes.
Solenoid Coil Temperature Ratings.
Coil winding have several temperature classes and are usually designed depending on the media, ambient temperatures and duty cycle (duty cycle being the power on time and power off cool down time) as all coils generate heat when energised a bit like a light bulb the more power they consume the hotter they will get. 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
Class F coils
are rated to 155C, basically the copper wire windings can withstand a working temperature up to but not exceeding 155 C. This are the most common form of solenoid coil and are ideally suited to working ambient temperatures up to 20 C and media up to 100C.
Class H coils
are rated to 180C, basically the copper wire windings can withstand a working temperature up to but not exceeding 180C. This are the most common form of solenoid coil and are ideally suited to working ambient temperatures up to 50 C and media up to 180C.
Class N coils
are rated to 200C, basically the copper wire windings can withstand a working temperature up to but not exceeding 200C. This are the most common form of solenoid coil and are ideally suited to working ambient temperatures up to 80 C and media up to 200C.
Why Do Solenoid Coils Burn Out?
Solenoid coils are designed to convert electrical energy into mechanical movement by means of a magnet field, which means as they consum power like a light bulb for example they will become hot, and the higher the wattage or power consumption or the longer they are swiched ON the hotter they can become.
If the coil becomes too hot or above its temperature rating (copper winding class rating) the copper or insulating material can fail to short circuit. Other reasons include high media or ambient temperatures preventing the coil from cooling sufficiently, water ingress between armature and coil or if the coil is removed whilst energised!!
Excellent Solenoid Valve Coil Manufacturer
For any distributor who wants to buy pneumatic solenoid coils in bulk, it is recommended to choose the manufacturer with the most competitive price. BRS is an excellent choice for those engaged in wholesale business. In the past 10 years, it has been the preferred electromagnetic coil supplier in Europe, America and other countries.
BRS can meet such requirements, and it will be a good choice when you consider choosing a Chinese electromagnetic coil. Here are 4 reasons why BRS may be a good choice for you:
More than 10 years of manufacturing and production experience in the field of coils
Our customized service can meet the requirements of different customers for coils.
Each order will comply with ISO 9000 QC standards, and there is no need to worry about product quality.
Lower prices, compared with other suppliers, our prices are more competitive.
If you need to buy pneumatic solenoid valve coils, please contact us or check our product list.
