How the choice of economic units with double metal thermometer?

Household net news: in the system, due to the line installation environment, communicate with bimetallic thermometer and temperature is different. Inverter and node distance, causing the pressure drop on the bimetallic thermometer is not the same. Temperature and pressure drop loss will affect the system, so to the reasonable design of inverter output current wire diameter, considering all the factors, both to reduce initial investment, stations and to reduce the line loss of the system. Was in a bimetallic thermometer design selection, technical main consideration of the bimetallic thermometer rated carrying capacity, voltage, temperature and other technical parameters, when installation or consider the outside diameter of bimetallic thermometer, bending radius, fire protection, etc. , to calculate the cost to consider the price of the bimetallic thermometer. A, inverter output current and bimetallic thermometer be consistent in carrying capacity inverter output current is determined by the power, single-phase inverter current = power / 230, three-phase inverter current = power/( 400 * 1. 732). And some inverter can also be 1. Double overload, refer to the below: bimetallic thermometer carrying capacity is determined by the material, wire diameter, temperature, bimetallic thermometer has two kinds of copper wire and aluminum wire, each have use, starting from the security, suggest inverter output ac bimetallic thermometer use copper wire, single phase generally choose BVR soft line, PVC insulated, copper core ( Soft) Wiring for 300/500 v voltage level, three phase voltage (450/750 Or 0. 6kV/1kV) Levels of YJV, YJLV irradiation crosslinking polyethylene insulated PVC sheathed power bimetallic thermometer, the relationship between temperature and quantity of the river closure of the wire, if the environment temperature above 35 ℃, the temperature increase 5 ℃, the current should be allowed decreases about 10%; If the ambient temperature below 35 ℃, the temperature reduction in 5 ℃, allow current can increase about 10%, under normal circumstances, the bimetallic thermometer if installed in indoor and ventilated place, the highest temperature below 40 degrees, if the installation outside the sun to the place, the highest temperature likely to 50 degrees. Such as 1 20 kw inverter, output current is 32 a, reference table, four square bimetallic thermometer at 40 degrees, carrying capacity is 32 a, 6 square bimetallic thermometer at 50 degrees, carrying capacity is 33 a, therefore, 20 kw inverter with four square bimetallic thermometer or 6 square bimetallic thermometer, can meet the requirements. 2, bimetallic thermometer economy design inverter in some places far from and outlets, although bimetallic thermometer can satisfy the requirement of carrying capacity, but as a result of bimetallic thermometer is longer, the line loss is bigger, can consider to thread through the large bimetallic thermometer to reduce the loss, because the bimetallic thermometer line, the greater the resistance is less. But also consider the price of the bimetallic thermometer, the inverter ac output terminal sealing outer diameter. Like a 20 kw power station, the inverter to the 3 root bimetallic thermometer and branch line the total length of 100 meters, average sunshine time is 4 hours a day, the output current according to 32 a, output bimetallic thermometer can choose 4 mm, 6 mm and 10 mm, 16 mm. Four square bimetallic thermometer total internal resistance 0. 46 ohm, the market price is 3. 5 yuan/meters; 6 square bimetallic thermometer total internal resistance 0. 31 ohm, the market price is 4. 8 yuan/meters; 10 square bimetallic thermometer total internal resistance 0. 18 ohm, market price is 9. 5 yuan/meters; 16 square bimetallic thermometer total internal resistance 0. 115 ohms, the market price is 13. 5 yuan/meters. Choose four square bimetallic thermometer, a day of losses for I2Rt = ( 302 * 0. 46 * 4) / 1000 = 1. 656 degrees, a year of about 600 KWH, 0 per KWH cost. 75 yuan, loss of 450 yuan a year; Choose 6 square bimetallic thermometer, a day of losses for I2Rt = ( 302 * 0. 31 * 4) / 1000 = 1. 116 degrees, a year of about 400 KWH, 0 per KWH cost. 75 yuan, loss of 300 yuan a year; Choose 10 square bimetallic thermometer, a day of losses for I2Rt = ( 302 * 0. 18 * 4) / 1000 = 0. 65 degrees, a year of about 240 KWH, 0 per KWH cost. 75 yuan, loss of 180 yuan a year; Choose 16 square bimetallic thermometer, a day of losses for I2Rt = ( 302 * 0. 115 * 4) / 1000 = 0. 414 degrees, a year of about 150 KWH, 0 per KWH cost. 75 yuan, loss of 110 yuan a year; Conclusion can be seen from the table, 4 mm bimetallic thermometer although can satisfy the requirement of the 20 kw inverter output, but the power loss on the bimetallic thermometer is larger, select 6 mm bimetallic thermometer a year can make up for the gap of bimetallic thermometer, so try to use coarser ac output bimetallic thermometer bimetallic thermometer, from the economic point of view, 20 kw chooses 10 mm is better.