How to Minimizing Unwanted Tripping on RCD (Residual Current Devices)

Why RCD / RCCB always tripping? The most commmon are as follows:
1. Leakage currents on the installation
2. Harmonics and high frequency leakage currents
3. Transient residual current on an installation (switch)
4. Surge currents caused by lightning strikes

How to minimizing unwanted / nuisance tripping on RCD?

1. Surge Protective Devices (SPD)
    -Install an SPD before the RCCB
    -Picture SPD refer to figure 1

2. Sizing RCD / RCCB
    -Estimated standing leakage current for electrical and electronics appliances
    -Picture of RCCB refer to figure 2

3. Auto Recloser or Auto-Reset RCD / RCCB
    -Install an auto-reset device RCD / RCCB
    -Picture of auto recloser refer to figure 3

Basic Protection Device for Residential (Electrical System)

In this post, I will brief about residential protection used in the electrical system. There are 3 primary devices safety:

1. Switch Fuses

Switch fuse used to protect and isolate circuit against overloads or overcurrent and short circuit as shown in Figure 1. When a fault occurs an overcurrent flows and the fuse element becomes hot and melts or “blows”.

• Advantages: Cheap and easy to replace
• Disadvantages: Oxidization

  

Figure 1: Switch fuse 1P+N

2. Miniature Circuit Breakers (MCB) 

MCB used to protect and isolate circuit against overloads or overcurrent and short circuit as shown in Figure 2. There are multiple type of MCB on the market but most common MCB used in residential is type C.

• Advantages: A faulted circuit may be restored
• Disadvantages: Expensive compare to Fuse

  

Figure 2: MCB 1P

3. Residual Current Circuit Breakers (RCCB) 

RCCB is used to protect and isolate circuit against earth leakage fault as shown in Figure 3. When a fault occurs, some of the current goes to ground thus create unbalanced between line and neutral. It send signal to tripping system.

• Advantages: Protect against electric short 
• Disadvantages: Expensive and need monthly test tripping

  

Figure 3: RCCB 1P+N