In solar or other DC power systems, there’s usually the need for a switch to safely disconnect circuits for maintenance or other reasons. That’s where the DC isolator switch comes in. For more about this type of isolator and what function it serves in a DC system, we suggest that you continue reading. We’ll explore the DC isolation switch and its common applications.
What is a DC Isolator Switch?
A DC isolator switch is a device that’s designed to provide safe isolation from direct current (DC) sources such as solar panel systems and batteries. It typically consists of two or more contactors that are activated by turning a handle or rotary switch, allowing the user to safely disconnect the circuit and isolate it from the power source.
The DC isolator switch is typically used in photovoltaic systems, battery storage systems, DC water pumps, electric vehicles, and other similar applications. You can mount indoors or outdoors, often depending on the type of system being powered by it.
DC Isolator Function
You can use the DC isolator switch in a few different ways. One of them is as an on/off switch to provide control over the system, or you can use it as a safety device to disconnect the power source during maintenance and repair work.
When it comes to safety, the DC isolator is a critical device. By completely isolating the power source when maintenance or repairs are necessary, it ensures that no one will be electrocuted if they come in contact with an energized part of the system.
An isolator switch with fuse protection also reduces the risk of damage to components and wiring due to short circuits. These usually occur when removing a live connection from a circuit or when a conductor comes into contact with a live part of the system.
Difference between AC and DC Isolator
The main difference between AC and DC isolators in the voltage they are meant to handle. While an AC isolator switch is used with AC voltages, a DC isolator switch is designed to only work with direct current sources.
That means the two types of isolator switches will have different ratings and capabilities. For example, DC isolator switches are typically rated at 20% higher than the circuits they are intended to isolate.
DC Isolator vs. DC Breaker
The DC isolator switch and DC circuit breaker are two components whose functions are often confused. But even though they are both used in power systems as safety devices, they look and operate differently, as the below points explain.
1. The DC isolator switch is used to safely isolate a system from its power source. It does not protect against overloads or short circuits like a DC breaker does, and must be fused for this purpose.
2. On the other hand, a DC circuit breaker is usually used to provide overcurrent protection in an electrical system. It will trip the circuit in case of an overload or short circuit, thus preventing damage to components and wiring.
3. The DC isolator also needs to be manually operated, often using a handle or other switch, and usually after the circuit breaker has been used to witch off or disconnect the circuit. Likewise, during re-connection, the isolator must be the first device to close.
4. A DC circuit breaker, in contrast, is automated and can switch the system off without any manual involvement from the user; that way, the circuit breaker acts as both an overcurrent protector and a disconnection switch for DC systems.
5. Another difference between a DC isolator vs. DC breaker is that a circuit breaker comes equipped with arc-suppression and shock-protection features. These are not present in an isolator switch, making it important to install fault current safety devices when using the latter.
How to Wire a DC Isolator Switch
The DC isolator wiring diagram is shown in the image above. Note that all connections must be made with the right type of wiring, depending on the voltage level of the system. It’s essential to use DC rated cables and terminals that are suitable for your particular system in order to ensure safety.
1. Before making any isolator switch connection, be sure to turn off all power sources before beginning work.
2. Additionally, make sure that all connections are secure and properly insulated. Once all wiring is confirmed, the DC isolator switch can be mounted in its position according to your system requirements.
3. Before wiring a DC isolator switch, read the manufacturer’s instructions and safety information. Failing to do so can result in serious accidents or damage to components.
4. When connecting the wires to the switch, make sure that all connections are secure and free of any debris or corrosion.
5. It’s also important to use the correct type and size of wire for the application. After all the wires are connected, make sure to check that the switch is working as intended.
DC Isolator Switch Price
The DC isolator price, when compared to that of a DC circuit breaker, is usually lower. However, the exact cost of a switch depends on the size and features that are included in it.
Basic models can start at around $20 while larger and higher-end models may cost upwards of $200. These isolator prices will vary considerably base on several factors such as:
- The size of the system
- The number of contacts
- The voltage that it’s designed for
Note that DC isolator switches are also available in different styles, and the design may vary from one manufacturer to another. Most often, this switch is a square box-like structure mounted on a wall or panel, and equipped with a handle or rotary switch.
The DC isolator switch provides a reliable means of safely isolating an electrical system or circuit. It allows users to quickly and conveniently disconnect the system without having to use additional tools or equipment. While they are not as sophisticated, DC isolator switches work alongside circuit breakers to ensure the safety of a DC system, especially during an emergency or maintenance session.