8 Common Failure of Slip Ring You Need to Know

by | Aug 10, 2021

The electrical slip ring is widely used in various applications. Also, it is no news that an electrician can make fault clearing and repairs of equipment maintenance without contacting professional engineers.

Here are some common faults of Slip Rings you need to know to make reasonable judgments of simple faults and timely maintenance.

1. Protection level

waterproof test

The standard protection level of a capsule product is IP51, and the standard protection level is IP54. Unless the customer specifically requires it, water can quickly enter the electrical slip ring when used in an environment more significant than 95% humidity, causing the product to short-circuit and burn.

When customers choose slip rings, they will try their best to provide all detailed information to the electrical slip ring manufacturer to make the most appropriate decision for the customer.

2. Signal interference

Electrical slip rings are often used overpowered and overloaded with signals simultaneously, which interfere with each other. This interference is divided into internal and external intervention and requires special shielding measures to prevent the interference.

Suppose you discover that the effect of the product is not good enough and the signal transmission is not up to the required signal transmission. In that case, you can check whether the product meets the requirements of signal protection during operation. You can only update the internal structure of the electric slip rings if you cannot solve the problem externally.

3. Short circuit and overload

If a slip ring is short-circuited after some time, it can result from the wearing out of the slip ring due to overuse. Or due to the closeness to the end of the slip ring service year. But generally, various reasons and factors may contribute to the short-circuiting of a new slip ring.

The electrical slip ring can be short-circuited due to the skipping of wire or the short-circuit of wire brushing. This situation may be due to increased fatigue resistance caused by the long-term movement of the wire of the slip ring brush. Or the bearing’s damage or vibration and the effects of the working environment on the internal structure of the slip ring. However, if there’s strong vibration under operating conditions, the thin-walled bearings inside the product may be damaged and break the spindle

4. Loose plastic and collector ring

When the plastic collector ring is pressed together by three copper rings for a while, the slip ring becomes loose due to shrink and crack in the plastic.

Like any other ring used in a mechanical device, the Loose slip ring is one of the most frequent faults developed by the slip ring. The shrinking and crack of the plastic and collector can also be a result of vibration and compression.

5. Carbon brush failure

slip ring and carbon brushes

The voltage distribution in the carbon brush of a slip ring can be altered when there is a sudden short-circuit or sudden load change. The imbalanced distribution of carbon brush current will result in an imbalance and abnormal voltage distribution at the switching segment.

6. Slip ring cooling

Due to the moveable contact of the slip ring with the carbon brushes, the electrical connection and friction between the slip ring and the carbon brush will always keep it warm. Keep an eye on the cooling fans and air passage of the slip ring. Always keep the slip ring away from the ambient air due to the moisture it contains. Airflow control sensors are generally installed in slip rings to ensure a smooth flow of cooling air. If the ring or cooling system has problems, you can install a temperature sensor to watch the slip ring temperature.

Ensure the proper sealing of the slip ring chamber to avoid air penetration into the slip ring chamber.

7. External failure of resistance

This slip-ring engine is assumed to be a wounded rotor induction motor in which the rotor windings are connected to an external resistor through the slip rings. This external configuration resistor is serially connected to the rotor winding, which has slipped behind synchronous speed due to a voltage.

The rotor voltage induced leads to an external flow and heat resistance. Resistors consume a significant amount of power during starting of the motor. It discharges this power as heat. The resistors’ temperatures are therefore raised.

8. Wearing out of essential components

repair slip ring

As a rule, you have to replace your ring brush at a quarter-inch when it gets worn out. If there are signs of breakage, collapse, or burning of carbon (which essentially is a carbon block with a metal springtail), the brush needs to be replaced.

The primary reasons for the wearing out of brushes and other components in a slip ring includes;

Low spring pressure: insufficient spring pressure may cause the brush to wear quickly. Springs of the clock and fingerstyle tend to lose strength when the brush is wearing, and over time, every spring fatigues. The effectiveness of the brush face is thus reduced, and the rate of brush wear increases.

Poor Commutation or Ring Condition: Accelerated brush wear may be caused by a rough or round contact surface. The electric and mechanic wear of the carbon brush can result from poor switching conditions. The springs are also flexed more often by an outside ring, resulting in shorter spring life and the risk of inadequate spring pressure.

The brush holder is unequally spaced or neutral: Incorrectly fitted brush holders can lead to several problems. Incorrectly installed brush holders can improve brush wear and damage the contact surface.


Persistent fault in the slip ring failure won’t only affect your productivity. It will also result in overstressing yourself. Following this guide will help you in getting familiar with the common fault a slip ring can develop. Besides, you will find it easy to deal with the faults and hence, increases your productivity.