Views: 226 Author: Site Editor Publish Time: 2022-12-21 Origin: Site
Traditionally, there is three way to do fail safe:super capacitor, batter backup, and spring return.
3 methods for electric valves to fail-safe positions with electric actuators—super capacitors, battery backup, and spring return.
An emergency signal triggers the backup device to open or close the valve immediately without any external ,And internal power source.
This emergency signal can be:
• An unusual event (fire, overflow, etc.)
• An automatic control signal
• An operator action
• electricity failure
Fail-safe electric actuators can drive the actuator to the desired fail-safe position when external power is applied
unavailable. There are two basic approaches to implement fail-safe functionality:
1) Store electrical energy, which can replace the external power supply to power the motor
2) Store mechanical energy to physically drive the gearbox independently of the motor.
We produced electric actuator, inbuilt farad capacitor to reach fail safe function, and we recommend super capacitors .all MTD electric actuator valve make Farad capacitor to fail safe electric actuators.
in the following text, i am going to introduce super capacitor:
The farad capacitor belongs to the electric double layer capacitor. It is the largest electric double layer capacitor that has been put into mass production in the world. Its basic principle is the same as other types of electric double layer capacitors. It is composed of activated carbon porous electrodes and electrolytes. The electric double layer structure obtains a super large capacity.
The definition of the life of a farad capacitor is related to the allowable attenuation rate of capacity/resistance, temperature, and working voltage. Usually, the cycle life of a farad capacitor is about 1 million times, and the life span can reach several decades.
The specific reasons are as follows:
First, as a chemical component, a farad capacitor is very different from an ordinary battery. Even in the process of storage, it will not undergo any chemical reaction, thereby reducing its service life, so this is another It is beyond the reach of ordinary batteries.
Second, farad capacitors are green and environmentally friendly products. During use, they can be charged indefinitely, and their lifespan will not be reduced during energy transmission. Therefore, farad capacitors are preferred as power storage devices in many industries or equipment .
Third, because the farad capacitor can be repeatedly charged and used repeatedly, and its charging times can even be 500 times that of other ordinary batteries, its service life is very long.
Farad capacitor features:
The charging speed is fast, charging for 10 seconds to 10 minutes can reach more than 95% of its rated capacity;
Long cycle life, the number of deep charge and discharge cycles can reach 10,000 to 500,000 times, and there is no "memory effect";
High-current discharge capacity is super strong, energy conversion efficiency is high, process loss is small, and high-current energy cycle efficiency is ≥ 90%;
High power density, up to 300W/KG~5000W/KG, equivalent to 5~10 times of the battery;
There is no pollution in the composition of raw materials, production, use, storage and dismantling of the product, and it is an ideal green power source.
Therefore, the traditional thinking way, say farad capacity disadvantage is rechargeable time, and service life short, and reliant on motor, but we use brushless motor, about brushless motor, please go ahead to next article.
Spring return electric actuators,
When the power supply is normal, the actuator can drive the valve normally and compress the spring at the same time, the spring after compression
The spring is held in a charged state by an electromagnetic brake.
When the electromagnetic brake is de-energized, the spring can drive the actuator and the valve to reach the safety of fully open or fully closed.
full location. The matching damper can control the speed of spring return to avoid excessive force on the valve
Once power is restored (without resetting the spring), the actuator returns to normal operation immediately
There is big difficult challenge : Electro-mechanical spring actuators, carry big size of electric actuators, and heavy weight, which is not good at shipping and installation carry.
In Summary, MTD electric actuator use farad capacitor to achieve fail safe function, when power off, valve automatically open or close. In this context, we don’t discuss battery backup , because it is the most unreasonable method to control fail safe, regarding to express shipping, sea shipping, costs, and high technology.