Siemens inverter external resistor heating measuring device DC output voltage of about 550 volts, and the normal only about 10 volts, what is the cause?
A: What you are talking about is the braking resistor. It is not always in operation. It is controlled by the built-in braking unit of the inverter or an external braking unit. The brake unit is actually equivalent to a switch. The inside is the IGBT as the switching element. The brake unit is connected in parallel with the intermediate DC bus of the inverter. When the DC bus voltage is too high (generally in the power generation operation state, such as re-braking, or heavy-duty lowering conditions, etc.), the brake unit detects that the voltage exceeds its setting. The fixed value, the IGBT is turned on, and the braking resistor is incorporated into the DC bus through the braking unit. Current flows through the braking resistor and consumes energy. Reduce the DC bus voltage to normal.
The normal state you are talking about is about 10V. It should be in the state where the brake unit is not conducting and the braking resistor is not working.
If turned on, the DC output voltage is about 550 volts, which is normal, much higher than this. For example, the Siemens brake unit has a high threshold of 774V and is turned on. The low threshold is turned on at 673V. The voltage has dropped a lot when you measured it.
The braking resistor must be heated, and the braking energy is consumed by the heat energy, so this method is not environmentally friendly and does not save energy. More advanced should be to feedback the brakes and return the energy back to the grid. However, small-capacity inverters are generally brake unit + braking resistor mode, because the power is small, which is more convenient, simpler, and also cost-effective.
There is also a fault condition. For example, the brake unit is broken, and the state is always turned on regardless of the state, so that the resistor is always connected, and the resistance continues to generate heat. This situation you should be able to observe.
In addition, the determination of the braking power is more complicated. In many cases, the braking unit and the braking resistor are selected by experience. It is not excluded that the braking resistor is selected. The resistance heat is very serious. In this case, the power of the braking resistor can be appropriately increased (several parallels, but the total resistance cannot be changed), which is when the braking power is not much different. If the difference is too large, simply increase the power of the braking resistor, and the brake unit will not be able to withstand it, which will be bad. It is necessary to add the brake unit and the braking resistor.
KNL4-100 Residual Current Circuit Breaker
KNL4-100 Moulded Case Circuit Breaker is MCCB , How to select good Molded Case Circuit Breaker suppliers? Korlen electric is your first choice. All moulded Case Circuit Breakers pass the CE.CB.SEMKO.SIRIM etc. Certificates.
Moulded Case Circuit Breaker /MCCB can be used to distribute electric power and protect power equipment against overload and short-current, and can change the circuit and start motor infrequently. The application of Moulded Case Circuit Breaker /MCCB is industrial.
Korlen electric also provide Miniature Circuit Breaker /MCB. Residual Current Circuit Breaker /RCCB. RCBO. Led light and so on .
KNL4-100 Molded Case Circuit Breaker,KNL4-100 Small Size Molded Case Circuit Breaker,KNL4-100 Electrical Molded Case Circuit Breaker,KNL4-100 Automatic Molded Case Circuit Breaker
Wenzhou Korlen Electric Appliances Co., Ltd. , https://www.zjaccontactor.com