ACREL AKH-0.66 L Square Hole Leakage Current Transformer

The ACREL AKH-0.66 L Square Hole Leakage Current Transformer is a residual current transformer (also known as a zero-sequence or earth leakage CT) built for low voltage switchboards and distribution boards. Rather than measuring load current directly, it senses the small imbalance current that occurs when there's an earth fault or insulation breakdown somewhere on the circuit, and outputs a proportional signal that a monitor or relay can act on.

How it works

• One or more phase conductors (or a busbar) pass through the transformer's window.
• Under normal, balanced conditions, the magnetic flux created by the conductors cancels out and the transformer produces no output.
• If current is leaking to earth anywhere on the circuit, the currents no longer balance, and the resulting net flux induces a small secondary current.
• This secondary signal (5mA) is sent to a connected device, such as an Acrel ARCM electrical fire monitor, ARD motor protector or ASJ residual current relay, which can then alarm or trip based on the leakage level.

Why choose this product

• It's purpose-built to work with Acrel's own fire monitoring and protection relay range, so signal levels and wiring are already matched.
• The square hole design fits over busbars or bundled cables, rather than being limited to a single round conductor.
• Five window sizes are available across the series, making it easier to match the transformer to the physical space and conductor arrangement in the switchboard.
• Class 1 accuracy suits monitoring and protection applications where a reliable leakage reading matters.

Benefits

• Provides an early warning signal for earth leakage and insulation faults, ahead of them developing into a bigger issue.
• Suited to busbar and multi-cable arrangements, not just single round cables.
• Straightforward to specify into a switchboard, since output, burden and accuracy class are fixed across the model range.