Video transcription 

Good day and welcome to this on-line training course.

In this video, we will examine timing principles as applied to circuit breakers.

This course was produced by Zensol Automation in collaboration with Hydro-Québec,

At the conclusion of this video, the participant will be able to recognize the different types of transducers and their installation procedure.

Location of displacement transducers and installation procedures.

What are the types of displacement transducers?

Displacement transducer installation examples.

A few recommendations for transducer installation.

What are the types of displacement transducers?

There are several types.

Some are designed for linear motion.

Others are designed for rotary motion.

Some are of the analog type, such as the resistive transducers, either linear or rotary.

Others are of the digital type, such as optical encoders.

The manufacturers of circuit breaker analyzers such as Zensol are able to give you all the details on which transducers are compatible with their respective instruments.

To be used, these transducers must be mounted on mechanical adapters to capture and record the motion of the breaker’s moving contacts.

For example, the ZLR mechanical kit uses rotary transducers because it converts any linear motion into rotary motion.

Installation example on a KSO type bulk oil breaker.

The breaker mechanism’s motion gives a good idea of what type of transducer and mechanical adapter to use.

If it is strictly linear, as in the case of the KSO, a ZLT 600 transducer and a ZLB mechanical adapter are used, as shown in this slide.

Example of displacement and instantaneous speed curves recorded on a bulk oil circuit breaker.

Installation example on an AREVA HGF type breaker.

In this example, three rotary transducers are used, one on each phase.

In addition to the three Zensol ZMS mechanical adapters used, some coupling adapters needed to be developed, as shown in this slide.

Here are the curves recorded on the Areva HGF three-phase circuit breaker.

Some recommendations for installing transducers.

Two steps are needed to measure the displacement of a circuit breaker’s moving contacts.

The first step is to select the right transducer, so it precisely records the motion of the moving contact.

The second step is to choose the right mechanical base and all the associated accessories such as special rods, specific bolts, and the particular couplings that best adapt to the breaker.

This first photo shows how one can check the alignment of the motion mechanism using a good bubble level.  The ZLR base is mounted vertically in this example.

One must also make sure that the rods attached to the moving contacts have grooves to avoid any slippage of the rod during operations.

In the case of linear transducers, it is good practice to check if the total travel of the breaker is within the limits of the transducer. Indeed, if it is not the case, the transducer will be damaged during a close or open operation.

Question lesson 3.

To perform a displacement test on a KSO type bulk oil breaker, what is the type of transducer used?

1. Linear transducer.
2. Rotary transducer.
3. A rotary transducer combined with a linear-to-rotary motion converter

The answers are: A) a linear transducer (see slide 5) or C) a rotary transducer combined with a linear-to-rotary motion converter (see slides 4 and 5 for more details).

References

Circuit breaker timing

Circuit breaker libraries