Can DCL actuators be used at high altitudes?
High altitude environments are more specialized and have an impact on the performance of DCL electric actuators. This report will evaluate the use of DCL electric actuators at an altitude of 3000 meters.
- Mechanisms of the effects of high altitude on electrical products
- Effects of the environment at 3000 meters above sea level on mechanical structures
- Impact of the environment on motors at an altitude of 3000 meters
- Impact of 3000 meter altitude environment on servo controllers
- Environmental effects on capacitance at 3000 meters above sea level
- Effects of an environment at 3000 meters above sea level on other electrical components such as potentiometers and microswitches
- Assessment findings
I. Mechanism of the impact of high altitude on electrical products
As you gain altitude, the air becomes thinner and the temperature gradually drops, which can lead to a range of outcomes.
1. The effect of lower air density and lower air pressure:
- Causes a reduction in the strength of the outer insulation. According to the empirical data, the elevation of 5000 meters below sea level, every 1000 meters, the average air pressure decreases 7.7 ~ 10.5kPa, the outer insulation strength decreases 8% ~ 13%.
- The breakdown voltage of fixed electrical gaps is reduced. To ensure that the electrical is not broken down at an altitude of 3000 meters, the electrical gap needs to be increased to 1.45 times the zero altitude.
- Reduce the medium cooling effect and increase the temperature rise of the product. Below 5000 meters above sea level, the temperature rise of the motor increases by 1% for every 100 meters of elevation.
- Lubricants are more likely to evaporate and gases or liquids are more likely to leak from sealed containers
2. The temperature decreases, and the temperature difference between day and night is large. Lower temperatures can compensate for the motor temperature rise; the larger temperature difference makes the shell more easily deformed, the sealing container is more likely to rupture.
3. Reduced precipitation and lower absolute air humidity. Lower absolute air humidity makes the outer insulation of the product lower, the motor commutator spark increases, and increases the wear of carbon brushes.
4. Higher solar radiation. Accelerated aging of organic materials leads to a reduction in organic insulation strength.
In summary, the effects of high altitude on electrical equipment are mainly in the areas of insulation and temperature rise, and the effects on mechanical structures are mainly in the areas of air pressure and low temperature.
II. Impact of the environment at an altitude of 3,000 meters on mechanical structures
There is no effect on the mechanical mechanism of the DCL electric actuator in terms of air pressure. The effect of low temperatures is mainly to increase the viscosity of the bearing and gear grease, thus affecting the output torque. However, as long as the ambient temperature does not fall below -25°C, the actuator can reach the rated output torque.
As the actuator parts are sealed within the shell, the shell strength is high, and the surface is sprayed with outdoor powder, excellent weather resistance, so the altitude of 3,000 meters of the region on the mechanical structure of the impact can be ignored.
III. Impact of the environment at an altitude of 3,000 meters on the motor
1, the impact of the motor temperature rise. According to GB755-87 basic technical requirements for rotating motors and GB5171-2002 general technical requirements for small-power motors, the amendment on the temperature rise limit value points out that: when the specified maximum ambient temperature is between 40℃ and 60℃, the temperature rise limit value should be subtracted from the value of ambient temperature exceeding 40℃. DCL is used in the maximum ambient temperature of 60℃, and under normal circumstances, the temperature rise limit value of the motor with the insulation level of E is 75℃. The maximum ambient temperature for DCL use is 60℃, while the temperature rise limit value for motors with insulation class E is 75℃ under normal circumstances. Therefore, the temperature rise of DCL actuators at an altitude of 3,000 meters above sea level can satisfy the above standard requirements as long as the temperature rise is not greater than 55℃.JBT 8219-2016 ordinary and intelligent electric actuators for industrial process control systems require that the temperature rise of electric actuators should not be greater than 60℃, but the temperature rise of our DCL series products is less than 50℃ both in field use and type test, so they meet the requirements of temperature rise in GB755-87.
2, the motor insulation strength of the impact of the DCL products used in the motor of the normal insulation resistance requirements of no less than 100 MΩ, according to each elevated 1,000 meters, the outer insulation strength reduced 10% calculation, the altitude of 3,000 meters, the insulation resistance down to 72.9 MΩ, and GB5171-2002 general technical requirements for small-power motors in the provisions of the normal insulation resistance of the motor is no less than 20 MΩ can be.
3, the impact on the mechanical properties of the motor. If the ambient temperature is too low, it will affect the rotor bearing of the motor, thus affecting the start-up of the motor, at this time it is best to use low temperature bearings. In addition, it will increase the wear and tear on the carbon brushes of DC brush motor.
Fourth, the altitude of 3,000 meters of the environment on the servo controller
Since the electronic components of the servo controller used in DCL actuator are sealed in the shell with epoxy glue, and the creepage clearance of each component has enough margin, therefore, the altitude of 3,000 meters environment has an impact on the servo controller.
V. Impact of the environment at an altitude of 3000 meters on capacitance
GBT 3667.2-2016 a.c. motor capacitor standard, for capacitor normal use conditions require altitude of not more than 2000 meters. The standard requires that the capacitor withstand voltage value is not less than 1.5 times the rated voltage, DCL series capacitors actual withstand voltage value are more than 2 times the rated voltage. Take the rated voltage 220V as an example, the standard requirement of capacitance withstand voltage value of not less than 220*1.5=330V for the following 2000 meters above sea level, and the corrected value of the electrical gap for 3000 meters above sea level is 1.13 times of 2000 meters above sea level, i.e., the capacitance withstand value for 3000 meters above sea level is required to be not less than 330*1.13=372V, and the DCL capacitance withstand voltage value is actually 450 V. Therefore, the environment of 3000 meters above sea level does not affect the capacitance. 3000 meters above sea level does not affect the normal use of the capacitor.
VI. Impact of an environment 3000 meters above sea level on other electrical components such as potentiometers and microswitches
Potentiometers, microswitches and other electrical components in the performance parameters of the altitude or air pressure environment are no requirements, their insulation resistance are greater than 100 MΩ, and motor requirements are the same. Microswitch withstand voltage 1500V.A.C (1min,10mA), potentiometer withstand voltage 500V.A.C (1min,10mA). According to the elevation of 5000 meters below sea level, every 1000 meters higher, the insulation strength is reduced by 10% calculation, the elevation of 3000 meters, microswitch and potentiometer withstand voltage were reduced to 1094V.A.C (1min,10mA) and 365V.A.C (1min,10mA).
VII. Conclusions of the assessment
According to JBT 8219-2016 Standard for Common and Intelligent Electric Actuators for Industrial Process Control Systems, the atmospheric pressure of the environment where the electric actuators are used should be within the range of 86kPa to 106kPa, i.e., the altitude should not be higher than 1,300 meters above sea level. Therefore, the environment of 3000 meters above sea level puts forward higher requirements for electric actuators.
From the analysis above, it is clear thatDCL series electric actuators have no effect on their performance when used at an altitude of 3,000 meters because the design parameters of each component have higher requirements, and there is enough margin in the design of electrical clearance and temperature rise. However, since the insulation withstand voltage has been reduced (about 72.9%), it is necessary to ensure that the grounding is secure when using in this environment.
At present, DCL series products have been used in Delingha area of Qinghai, which is at an average altitude of 2,980 meters, and the current use situation is normal, which also supports the above assessment conclusion.
Egong.com.cn 42018502006527 No.
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