A DC isolator switch is an important manually operated electrical safety device commonly used in electrical systems such as photovoltaic power generation systems and battery energy storage systems. It can easily shut down the circuit during post-maintenance and troubleshooting, providing a layer of protection between the user and the electrical system components. Users deeply recognize and love the stable structure and convenient operation.
Whether it is indoors or outdoors, DC isolator switches can be installed, depending on the type of electrical system used for power supply.
Importance of DC isolator switches in photovoltaic systems
The DC isolator switch is an important safety device in solar photovoltaic systems. It is used to manually disconnect the connection between various components in the photovoltaic system to ensure the safety and stability of the system.
The DC isolator switch is specially used to disconnect the circuit in post-maintenance or emergency situations, isolating the solar panel from the AC side, so a DC isolator switch is usually installed between the solar panel and the inverter.
The DC isolator switch is very important. The reliability of this safety device directly affects the stability of the photovoltaic system. With the popularity of photovoltaic systems, industry standards are gradually improving. According to the IEC 60364-7-712 standard, each photovoltaic system now needs to be equipped with a DC isolator switch on the DC side.
Choose the right DC isolating switch to ensure compatibility with the various components of the photovoltaic system to ensure the best operation of the photovoltaic system.
How to choose a DC isolating switch?
There are four key points to consider when choosing a suitable DC isolating switch for an electrical system:
Choose a brand that has passed international certifications, such as IEC and UL certifications, which ensure that the product meets safety standards. IEC certifications such as IEC60947-3 specify the basic performance and test requirements of isolating switches. UL certifications such as UL508i differ from IEC in some parameters, which is a requirement of the US market.
Select by system voltage. The rated working voltage of the DC isolating switch should be greater than the system requirements, the maximum power point voltage, and the open circuit voltage of the system components. Consider the power of the system components, whether they are connected in parallel or in series, etc.
Consider the application environment. Select the appropriate DC isolating switch according to the requirements of the application environment, considering the working environment temperature, IP level, fire rating, etc. Also consider the appropriate installation method according to the application environment, such as panel mounting, wall mounting, etc.
Considering the functions of the DC isolating switch, a qualified DC isolating switch should have a good arc extinguishing function, a shell made of highly flame-retardant material, a high protection level, a reliable disconnection function, and a small on-resistance.
What is the difference between AC and DC isolating switches?
The main differences between AC isolating switches and DC isolating switches are the following five points: the type of current handled, the voltage and current ratings, the internal structure and components, the application scenarios, and the state switching speed.
Type of current handled: DC isolating switches are specifically used to handle DC current that flows constantly in a single direction, while AC isolating switches are specifically used to handle AC current that changes direction periodically.
Voltage and current ratings: In order to meet the different needs of DC and AC electrical systems, the voltage and current ratings are also different. The various ratings of DC isolating switches are related to DC power supplies, while the various ratings of AC isolating switches are applicable to AC power distribution systems.
Internal structure and components: In order to handle the two different current waveforms of DC and AC, the internal structures and components of the two isolating switches will also be different.
Application scenarios: DC isolating switches are used in DC power supply systems, such as solar panel systems, battery energy storage systems, etc. AC disconnectors are used in AC power distribution systems, such as residential and commercial electrical systems.
State switching speed: Due to the different characteristics of AC circuits and DC circuits, the two types of disconnectors will also have a large difference in state switching speed, which will affect the disconnector’s ability to cope with voltage and current.
The difference between DC circuit breakers and DC isolator switches
The main difference between DC circuit breakers and DC isolator switches is the difference in function and internal structure.
Functional difference:
DC circuit breakers are mainly used for overload and short-circuit protection and have the ability to automatically cut off fault current. DC circuit breakers also have a longer service life and can cut off larger short-circuit currents multiple times without damage. They are often used as a protection mechanism for DC systems.
DC isolator switches are mainly used to manually isolate DC power supplies and have no overcurrent protection function. In actual use, the cutting capacity is limited and can only cut off a small current. It is used to manually isolate solar panels from inverters to provide further protection for operators during later maintenance and troubleshooting.
Internal structure differences:
DC circuit breakers have relatively complex contact systems, arc-extinguishing devices, and trips.
The structure of DC isolator switches is relatively simple.