Troubleshooting a Circuit Breaker That Keeps Tripping: Causes and Solutions

What is Aptomat?

Definition of Aptomat

Aptomat is a Russian term used to refer to an automatic switching device, also known as an automatic switch, abbreviated as CB (Circuit Breaker) or simply called At. It plays a vital role in the electrical system by protecting the circuit and preventing overload, short circuit, voltage drop, reverse power transmission, electric shock, leakage protection, and thermal protection.

Aptomat Classification

– Based on structure:

Aptomat MCB type (Miniature Circuit Breaker) and Aptomat MCCB type (Moulded Case Circuit Breaker) have the function of protecting against current overload and short circuit.

– Based on phase/pole number:

• Single-phase Aptomat: 1 pole
• Single-phase Aptomat + neutral (1P+N): 2 poles
• Two-phase Aptomat: 2 poles
• Three-phase Aptomat: 3 poles
• Three-phase Aptomat + neutral (3P+N): 4 poles
• Four-phase Aptomat: 4 poles

– Based on function:

• Normal Aptomat: MCB and MCCB with overload and short circuit protection.
• Leakage protection Aptomat: RCCB (Residual Current Circuit Breaker), RCBO (Residual Current Circuit Breaker with Overcurrent Protection), and ELCB (Earth Leakage Circuit Breaker).

– Based on short circuit breaking capacity:

• Low breaking capacity: Usually used in residential buildings.
• Standard breaking capacity: Usually used in industrial applications.
• High breaking capacity: Usually used in industrial applications and special applications.

– Based on adjustable current rating:

Aptomat with fixed current rating and Aptomat with adjustable current rating.

Structure of Aptomat

The structure of Aptomat consists of the contact, arc extinguishing chamber, tripping mechanism, and Aptomat protection hook.

Contact of Aptomat

Aptomat usually has two levels of contact. The main contact is used for conducting electricity, and the arc contact is used to prevent the arc from spreading to the main contact. When the Aptomat closes the circuit, the arc contact closes first, followed by the auxiliary contact, and finally the main contact. When cutting off the circuit, the main contact opens first, followed by the auxiliary contact, and finally the arc contact.

Arc extinguishing chamber of Aptomat

The arc extinguishing chamber is usually divided into many short segments with steel plates stacked into mesh partitions to facilitate arc extinguishing. It comes in two types: half-enclosed type and open type, which are used to extinguish arcs in different working modes of the electrical system.

Tripping mechanism of Aptomat

The tripping mechanism of Aptomat is usually controlled manually and by electro-mechanical means such as an electromagnet or electric motor. Hand-operated tripping is performed with Aptomats with a rated current less than 600A, while electromagnetic control is used in Aptomats with a current rating of up to 1000A.

Aptomat protection hook

The protection hook of Aptomat acts when the electrical circuit shows signs of overcurrent, helping the Aptomat automatically cut off the power to prevent accidents. The overcurrent protection hook is usually made from an electronic hook system and a thermal relay, while the voltage drop protection hook is usually an electromagnet.

Principles of Aptomat operation

For Aptomats with a maximum current rating, they will be in a closed contact state when the power supply is closed. When the circuit is overloaded or shorted, the electromagnetic attraction force will cause the contacts of the Aptomat to open, disconnecting the electrical circuit. For Aptomats with low voltage, excessive voltage drop will also cause the contacts to open and disconnect the circuit.

Reasons for Aptomat tripping

There are several reasons why an Aptomat keeps tripping:

– Overloaded circuit: Excessive power consumption due to using too many electrical devices at the same time.

– Main electrical line has a fire or short circuit: Problems with the main electrical line can destabilize the Aptomat and cause it to trip.

– Electrical leakage: Incorrectly connected wires or hidden wire problems can cause electrical leakage and trip the Aptomat.

– Aptomat malfunctions: Worn-out contact points or poor-quality Aptomats can cause frequent tripping.

How to troubleshoot Aptomat tripping

To troubleshoot continuous Aptomat tripping, follow these steps:

Step 1: Prepare necessary tools such as a screwdriver set, a new Aptomat, a shock protection Aptomat, and an electrical meter.

Step 2: Turn off the power of the devices being used and turn on the Aptomat. If the Aptomat doesn’t trip, then the electrical devices in the house are malfunctioning. If the Aptomat still trips, proceed to Step 3.

Step 3: Remove the switches and electrical sockets and separate the positive and negative ends. Turn on the Aptomat, and if it keeps tripping, then the cause is likely a fault in the hidden electrical wiring. Proceed to the next steps.

Step 4: Directly connect the shock protection Aptomat to the input power source, and install the electrical wires one by one into the output of the shock protection Aptomat. If any wire causes the shock protection Aptomat to trip, it means that wire is damaged.

Step 5: Replace the old electrical wires with new ones and reinstall them. Use a power drill to run a new electrical wire in the wall if needed.

Above is an article that provides information about what Aptomat is, the reasons for Aptomat tripping, and how to troubleshoot it. If you have any questions, please leave a comment below!