# LV MCCB Testing (IR Test)

**URL:** <https://forumautomation.com/t/lv-mccb-testing-ir-test/12719>\
**Category:** Electrical\
**Tags:** test\
**Created:** [October 18, 2024, 4:07pm UTC](https://forumautomation.com/t/lv-mccb-testing-ir-test/12719 "2024-10-18T16:07:10Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [October 18, 2024, 4:07pm UTC](https://forumautomation.com/t/lv-mccb-testing-ir-test/12719/1 "2024-10-18T16:07:10Z")

</div>

This is practical work for testing and pre-commissioning the LV MCCB using the guidelines to guarantee that the work is carried out in accordance with the plan requirements.

 ![image](https://cdn.forumautomation.com/original/2X/d/d4c8f38098bdf742e94dc746a72767363d9b6d89.jpeg)

After separating all incoming and outgoing cables.

IR for PVC insulated cables is to be a minimum of 100 Megaohm-km, and for signal cables: 10,000 M.

All measured phase-to-phase and phase-to-ground distances must meet the criteria.

> # Procedure

Using an IR tester, apply 1000 Vdc between phases R, Y, and B to load terminals A, B, and C for 1 minute with the CB position set to off.

Using an IR tester, apply 1kVdc between phases R, Y, and B to the ground terminal for 1 minute with the CB in the ON position.

Most likely, the same approach is used throughout all phases.

With the CB turned on, apply a DC voltage between phases R and Y for one minute.

1. For 1 minute, apply the DC voltage between phases Y and B with the CB switch turned on.

2. For 1 minute, apply the DC voltage between phases R and B with the CB switch turned on.

The IR range refers to how well a capacitor’s dielectric material resists leakage current. Leakage current measurements after applying DC voltage are typically very modest, in the nano-ampere range.

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