Category: Industry Trends

This basic course covers the fundamentals of the Relion® portfolio.

Participants will explore the key features and operations of Relion

devices, as well as setting and engineering with PCM600. The course

is designed as a foundational course, taking a comprehensive approach to

ensure thorough understanding by combining theoretical sessions with

practical, hands-on exercises guided by our experienced instructors.

Course type and methods

This is an instructor-led course with interactive discussions and practical exercises. 

The training is conducted in a hybrid format, with sessions takingplace both on-site in Vaasa,

Finland, within our classroom facilities, and online.

Participants joining online will be granted secure remote access (VPN) to relays physically located in

our Vaasa, Finland classroom premises.

Transients affecting AF coils

Voltage peaks/transients are not uncom mon especially in poor quality or weak net

works. Too high voltage peaks/transients may cause damage to the AF coil. The

AF coils are designed to handle certain peaks/transients and have been tested to

meet relevant IEC standards.

Spare parts and warranty claims

Inspection intervals

The intervals between inspections are determined by the design and operating condi

tions of the contactor.

If advise is needed on a specific application please contact ABB

Spare parts

Basically these contactors are considered maintenance free. Based on reasons above

occasionally there could be a need to change certain parts. Following parts are consi

dered contactor spare parts and can be found in ABB product catalogs or on ABB web

site:

• Main contact sets

• Arc chutes (recommended to be changed at the same time as the main contacts)

• Contactor coils

• Auxiliary contact blocks

Note: Use only ABB original spare parts to ensure product reliability

PLC control of AF400 and above

Make sure the dip switch is in the correct position for proper operation  See picture

below. Position A when using PLC control and position B for conventional operation (default).

High temperature readings

When concern of high temperatures on and around the contactor please check

the following (also see picture below for max permitted temperatures).

•  Make sure the connections are properly torqued.

•  Make sure the cable size is what is recommended in our catalogs.

•  Make sure the correct coil is selected for the applications.

Measurement of the resistance of the main contacts is not recommended since only

advanced equipment can be used to get a correct reading. Due to the location of the

armature the cover can reach very high temperatures (>100C). This is still within

acceptable limits.

Restarting with motor idling

– Attempting to restart the motor before it

has come to a full stop will cause a current peak that theoretically can reach twice the

current compared to starting the motor from a standstill. This can result in welded

contacts.

Star delta (wye-delta) starters

Change over time between star and delta

– Setting the change over time between star and delta too short will not allow the

motor to reach 80-90% of its nominal speed. This will cause the star contactor

to break a higher current than expected. If the starter stays in the star position for

too long of a period; this will increase the stress of the star contactor because the

star contactor is mainly sized for the short time current rating.

– The change over time between the star and delta is important. If no timer or other

device is used to get an idle time between opening of the star contactor and closing

of the delta contactor, there is a risk that the arc inside the star contactor could

remain and create a short circuit. If the elapsed time is too long, the motor starts to

decelerate and the delta closing will create a higher current peak than expected.

This can result in welded contacts. Generally the idle time should not exceed 50

ms. When AF is used no separate time delay is needed.

Product coordination

Lack of product coordination with fuse or breaker missing or wrongly sized can

cause excessive contact wear or lead to welded contacts.

For more specific information regarding short circuit protection coordination please see our technical

catalog 1SBC1001122C0202. section: General technical data.

Trouble shooting

examples of common reasons for contactors not working properly

Voltage drop during start up of the motor Voltage drop to less than 85 % of nominal

voltage for 5 to 10 ms can be enough for the contactor to start opening.

Also,other disturbances in the control voltage such as poor relay contacts or too small

control transformer/power supply could be responsible for this problem.

The result of these voltage problems can be increased

contact wear and also lead to welding of main contacts.

With the AF technology these problems are avoided.

Poor voltage to coil

Control voltage less than 85% during pick up may not be enough to safely close the

contactor and can cause the coil to meltdue to over heating. This because the coil

is designed to withstand the inrush current for a limited time only. One common

reason is when the coil supply is taken from the main supply were high current

is causing the voltage to drop. Too high continuous control voltage could also

cause the coil to melt. See picture below for typical failure.

Direct on line (across-the-line) motor starting.

Changing main contacts, arc chutes and coils

When changing the AF coil with its PCB (printed circuit board) care must be

taken to avoid ESD damage.

Before any dismantling of the contactor:Make dead by, turning off the contactor.

Opening the main circuit by turning off the main switch, if any, or by removing the

main fuses in all three phases. To protect against making attempt, open also the con

trol circuit.

Poor voltage to coil

Control voltage less than 85% during pick up may not be enough to safely close the

contactor and can cause the coil to meltdue to over heating. This because the coil

is designed to withstand the inrush current for a limited time only. One common

reason is when the coil supply is taken from the main supply were high current

is causing the voltage to drop. Too high continuous control voltage could also

cause the coil to melt. See picture below for typical failure.

Direct on line (across-the-line) motor starting.

Current peaks used by heavy duty starting- If the application requires a high level

of torque during start-up, for example a big fan or a pump, it is important that the

contactor’s making capacity and short time withstand current are capable of handling

the starting current and current peak.

Maintenance of contacts

A contact is not necessarily damaged or worn out, just because the surface is rough and

discolored. The contacts in the figure below may look like bad contacts but the fact is

that they are better than a new set of contacts. This is because they are ”electrically sea

ted” and make good contact over a larger surface. Based on this it would be completely

wrong to change a contact only by judging from the appearance of the surface. Also it

is quite normal that the contacts in the three phases are not evenly worn and because

of this all contacts both fixed and movable need to be changed. At the same time it is

recommended to change the arc chutes.

Inspection of contacts

With today´s high performance contactors, filing, grinding, or other attempts to restore

contacts or contact surfaces should be avoided. Our experience shows that filing and

grinding increases the risk of causing other problems. For example the risk of increasing

the contacts resistance  is high due to scrap from this grinding and filing.

Maintenance should be limited to inspection of the contacts for the level of contact wear.

This is to ensure a trouble free operation of the contactor until the next service is requi

red (see next section –Interpreting levels of electrical contact wear). At the same time

observations can be made to judge if the contactor operates well in the application and

that no signs of abnormal wear or damages are present on the contacts.

Contact bounce

The operational limit of the contactor is between 85 and 110% of the rated coil

voltage according to IEC60947-4-1. A voltage variation of ±5% of the above

limits will increase the contact bounce that leads to increased contact wear (does not

apply to AF with its electronic wide rangecoil). The reason for this is that higher

voltages will increase the speed of the electromagnet at closing. Lower voltages

will decrease the speed at closing. Both these factors can lead to a higher level of

contact bounce at closing. High voltage and the increased speed at closing also

contribute to some increased sound.

Pollution of the magnet pole surfaces will create a slight hum coming from the

contactor in the closed position. When cleaning, use a soft and dry piece of cloth.

Hum can also occur if the pole surfaces are deformed. A louder hum will occur if

the shading coil (does not apply to AF) is broken because the magnet will cause the

contactor to chatter. If so the complete contactor needs to be exchanged.

Another reason for AC-hum could be corrosion caused by environmental conditions that

exceed the contactor specifications.Contactors need to be protected from conden

sation in order to keep the pole surfaces of the magnet free from corrosion.

For more specific information regarding this please see our technical catalog

1SBC1001122C0202. section: General Technical Data.

Mechanical wear

The number of mechanical operations has a low impact on the life of the main

contacts and their overall electrical life.

However general information concer ning mechanical wear could be of interest.

AC-Hum

Pollution of the magnet pole surfaces will create a slight hum coming from the

contactor in the closed position. When cleaning, use a soft and dry piece of cloth.

Hum can also occur if the pole surfaces are deformed. A louder hum will occur if

the shading coil (does not apply to AF) is broken because the magnet will cause the

contactor to chatter. If so the complete contactor needs to be exchanged.

Another reason for AC-hum could be corrosion caused by environmental conditions that

exceed the contactor specifications.Contactors need to be protected from conden

sation in order to keep the pole surfaces of the magnet free from corrosion.

For more specific information regarding this please see our technical catalog

1SBC1001122C0202. section: General Technical Data.

Guidelines for Contactor inspection and maintenance

Some general advice

1. Choose correctly

• Nature of the duty

• Positioning of the contactor

• Voltage and frequency

• Frequency of operation

• Safety regulations

• Electrical and mechanical stresses

2. Mounting/installation

•  The instructions supplied with every

contactor should be followed.

•  In case of drilling in the panel make sure

to protect the contactor from falling

metal shavings that otherwise could

lead to excessive hum or flashovers.

3. Storage and climate

Consider the immediate environment

(variable temperatures, humidity, storage

conditions etc).

4. Connections

Make sure the recommended torque val

ues given in the instructions are followed

and that proper torque checks depending

on the application are done.