Circuit Breaker Services

To ensure your equipment operates reliably we recommend an appropriate maintenance plan for you LV & MV circuit breakers We attend vessels for regular maintenance and certification, but also for emergencies when an ACB is not functioning correctly. Our service plan enables us to service your breaker in situ if fixed or withdrawable or to remove and work on it at our premises. During the service we disassemble certain elements of the ACB to allow inspection, lubrication, repair and testing. We have a range of specialized secondary injection test equipment to enable us to test the operation of the ACB's electronic trip units and their parameters. Also we will check the Micro Ohm reading of the contacts. A portable primary current injection device up to shortly 9600Amp is also available. We will provide a certificate to handover to your Class surveyor.

Secondary Current Injection Testing

It is a method of connecting a secondary injection test set to a trip unit (trip device, over current module, protection device, OCR, ETU etc) on a circuit breaker and injecting a simulated current to prove it works at different levels.

Why is it important to Secondary Injection Test Trip Units during a breaker service?

The trip unit on a low voltage breaker (molded case or air type) is usually an option selected by the system or panel designer to provide protection to the site in the event of a fault or over current occurring. The trip unit measures the amount of current and calculates its effect on the site system against its settings (usually decided by a commissioning Engineer), and will trip or open the breaker as required. The larger the current measured, the quicker the breaker should trip or open.


It is an important test to carry out on a trip unit during a service.

By connecting one of our many different manufacturers secondary injection test sets we can ensure that the trip unit, its settings or factory parameters, and associated components are working as they should do. It is also a key test for a circuit breaker after a mechanical service and inspection, as the breaker is repeatedly charged, closed and opened.These sequences help ensure key lubrication has worked into the mechanisms that are often found dry and un-serviced. The test equipment types, and designs, vary greatly but all are designed to prove the breaker protection from very simple to complex methods.


Tests normally carried out, dependent on the specification of trip unit and tester are:

  • Long Time Trip Delay
  • Short Time Trip Delay
  • Instantaneous
  • Earthfault


Each of these tests are repeated several times, to ensure reliable, repeatable, operation and trip times. Any inconsistence could imply the trip unit is not working correctly hence not protecting the site systems. Infinity Electric B.V. are continually assessing customer and site requirements and invest in old and new secondary injection test equipment every year.


We pride ourselves on having a substantial range of key current, and obsolete, manufacturer test equipment that is maintained and calibrated for our use on site and in our workshop. On occasion where the breaker is obsolete and equipment is not available we use, where possible, our secondary injection tester to test breaker protection.

In case your ACB and her parts are obsolete we also can do retrofit services. We can test a various types of all widely used brands such as:

  • Merlin Gerin
  • Schneider Electric
  • Terasaki Electric
  • Hyundai Electric
  • ABB
  • General Electric
  • Siemens
  • Mitsubishi
  • Hitachi
  • Eaton
  • WEG
  • Hager
  • Larsen & Toubro
  • Etc.