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What are protection Modules? Why protection modules are required?
Protection modules are components used in the circuit or in the control panel to avoid the interference of noise.
Electrical apparatus used; may be enclosed (e.g., motors) or placed in the open (e.g., transmission lines). All such equipments’ undergo aberrations in their lifetime due to various reasons. It becomes necessary to avoid these abnormal operating circumstances for the safety and longevity of the equipment.
What is Noise?
Noise is an unwanted signal that combines with the original signal and this could be in a temporary or either in a permanent form. Noise gets generated in the electrical and electronic systems while transmitting signals.
The level of noise in any signal depends on the length of the cable, the proximity of the strongest signal in nearby cable and the other wires around the signal cable. For sensor and communication signals; especially noise is an enemy and it could tremendously degrade the quality of the signals.
It is difficult to eliminate noise from the surrounding but Connectwell has solutions that eliminates its effect from affecting your control system. This solution is known as protection modules.
Given below are scenarios that causes noise and solutions on how we can avoid it.
What Causes Noise?
There are two causes of noise, one being natural phenomena and the other is due to electrical and electromechanical instruments.
What are the Natural sources of Noise?
· Static electricity
· Thermal shot
· Solar radiation
The above mentioned are some of the natural phenomena that affect the electrical signal tremendously. Although this cannot be avoided; however we can prevent our equipment from damage.
Solutions to avoid interference through natural sources?
There are various solutions available in the market such as Surge Protectors, Earth-leakage circuit breakers, phase failure devices, metal oxide varistor, diode modules, RC circuits or fuse modules are used in the panels to protect your control panel from damage.
What are the sources of noise other than Natural Phenomena?
Other than the natural phenomena mentioned above there are other factors which causes the noise. I have listed a few of them below.
1. Electromagnetic interference
This is a major source of noise; if two cables are running parallel to each other, then the electromagnetic interference of one cable causes an effect on the other cable and noise gets induced in this second cable, this noise would change the potential of the signal which causes misbehaving of the devices running on that signal.
How to avoid electromagnetic interference
To avoid this noise, the signal carrying cables should be twisted in pairs. This would eventually nullify the electromagnetic effect.
2. Back E.M.F.
In components which include an induction coil, Back EMF is generated. The induction coil stores some part of the energy and in the absence of the main source it discharges itself. The discharge is typically of low period and high current, which acts as sure for the other component in the systems, typically a panel. E.g Relays, transformers, contactors produce Back EMF. This Back EMF eventually damages the other components.
How to avoid Back EMF?
Back EMF cannot be avoided, but it can either be utilised as energy or, it can be grounded. Railways employ the circuit in a way that while breaking the motors; the back EMF generated to provide back to the electric line. This involves complex and costly components and circuit design. For smaller application relays and transformers-a simple protection diode can be used.
3. Direct Electric contact-
This type of noise is generated due to common ground for the two different signals. In this case, the voltage variation in one signal causes variation in another, this is known as direct electric contact or Galvanic Noise.
How to prevent Direct Electric Contact type Noise?
Use separate signal cables for the return path cables. This would eliminate galvanic noise.
4. Electrostatic noise-
Following are some of the common reasons that cause electrostatic noise.
1. Two cables running parallel to each other generate an electrostatic capacitance. This generates the electrostatic noise. The electrostatic capacitance gets generated between the two signal cables and causes an additional voltage level in the signal.
2. The potential difference between two conductors is a source of noise.
3. A non-operating fluorescent bulb is a source of generation of noise due to fluctuation.
4. Open conductors also generate noise.
How to avoid Electrostatic noise-
By using the shielded cables the electrostatic capacitance eliminates the electrostatic noise.
5. Radio Frequency interference-
Tele-communication network uses radio frequency signals for communication. Around the globe, the telecommunication network has evolved tremendously. Gadgets like television, telephone, mobiles, radios/FM uses radiofrequency for communication and hence causes a glitch to the signal carrying cables. Although the radio signal effect on the signal cable is low as compared to other types due to the low signal levels when affected, it degrades the signal.
- How to avoid radio frequency interference-
Generally, radio frequency signals are fixed and hence the filter can be designed in such a way that the particular frequency signal can be avoided. A complex filter circuit is required for avoiding the radio frequency signals.
Connectwell offers various types of protection modules such as surge protectors, SPDs, fuse modules, diode modules and RC filters which will protect your instruments from noise and interference
- Surge suppression Terminal block
These are specially designed terminals with surge suppression unit and are generally used for protection from surges due to natural as well non-natural phenomena.
1. Terminal with MOV.
MOV stands for Metal oxide varistor. It acts as short circuit in case of surge at the input so that the extra voltage can be grounded and the output component can be saved from damage.
2. Terminal Block with Protection diode
Diodes are generally used for polarity protection as it blocks reverse current. This is generally used with inductive load which saves the equipment from back EMF.
3. RC protection terminal block
RC filter finds the application in various segments. To avoid radio frequency interference these modules are used. Noise generated through the electromagnetic interference can be nullified by using RC filters.
4. Terminal block with fuse.
There are multiple instances where the instrument damages due to the overcurrent. Using fuse module can save your instrument from damage.