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The 3-in-One Circuit Breaker Testing Powerhouse

September 09, 2025

CIBANO 500 is the perfect solution for testing medium- and high-voltage circuit breakers

Thousands of customers around the world appreciate and value the numerous advantages of the CIBANO 500. It enables efficient execution of essential circuit breaker measurements, such as timing, static and dynamic contact resistance, travel, coil current and motor current, applicable to breakers of all voltage levels. Its extensive capabilities and efficient test methods for testing high voltage breakers are well recognized. Additionally, its built-in voltage/current source allows assessment of breaker performance under special conditions, such as overcurrent, undervoltage, or inadequate DC supply.

This article demonstrates the capabilities of CIBANO 500, highlighting an additional feature set beyond the traditional testing methods unavailable in other dedicated circuit breaker testing devices.

Specifically for budget-friendly medium voltage circuit breakers that include an undervoltage release, overcurrent release, or lack a trip coil entirely, it is crucial to have this feature to evaluate and record operational performance.

Undervoltage Release Test

CIBANO 500’s undervoltage release test determines the specific control voltage level at which the undervoltage coil trips the breaker. The guided test procedure simplifies the examination of the undervoltage release significantly.

The test begins with the breaker entirely disconnected from the power supply. This means the main contacts are open because the undervoltage coil is not energized. As a first step, rated voltage is applied to the undervoltage coil, allowing the main contacts to close automatically via the closing coil using the CIBANO 500 or manually by the tester. Then, the supply voltage is gradually decreased until the release voltage threshold is reached, prompting the switch to open. At this point, the test is finished, and the release voltage is recorded.

What is the function of an undervoltage release?

In addition to the common trip and close coils, some breakers also include an undervoltage coil. This coil is typically found in breakers located in a substation which does not have a backup control supply power source, or where the control voltage is not supervised. The purpose of this undervoltage coil is twofold: firstly, it trips the breaker if the control supply voltage falls below a certain threshold (see IEC 62271-1:2017), and secondly, it prevents the breaker from reclosing while the control voltage level stays below an acceptable level.

Overcurrent Release Test

In the CIBANO 500 overcurrent release test, its stable and controlled power supply is used to determine the current threshold that activates the specific overcurrent release input of the breaker, causing it to trip.

CIBANO 500s overcurrent release test provides a gradual increase in current pulse to the overcurrent release input until the circuit breaker's main contacts are opened. The trip current is recorded and can be used for reporting or failure analysis.

Where are overcurrent releases used?

Beyond conventional protective relays, self-powered protective relays are capable of initiating overcurrent tripping in circuit breakers. These relays derive the energy required to operate from current transformers within the primary circuit. When an overcurrent situation is identified, the current that energizes the relay is also used to open the circuit breaker. This strategy eliminates the dependency on standard voltage for controlling the trip coil, utilizing an overcurrent release mechanism designed specifically for this purpose.

Motion Based Timing Test

There are cases where our customers must also determine the switching time of circuit breakers lacking an electrical release mechanism. The CIBANO 500 addresses this issue by concurrently tracking the movement of the main contacts. As a result, the commencement of time measurement is adjusted from starting point as defined in the IEC standard, from the moment when the trip/close coil is energized, to the time when the movement begins.