Battery energy storage systems (BESS)

Battery energy storage systems (BESS) are used to store power (often from a renewable source) for later use during a critical time. The benefits of these systems include cost savings, clean energy, and reducing downtime. It is vital that the electrical integrity of the systems is properly monitored to maintain the benefits.

Unearthed BESS


BESS most commonly operate as unearthed systems, which means all line conductors are intentionally isolated from earth. Although these systems can continue to operate with a single earth fault, it is vital to indicate and clear the first fault as quickly as possible. If the fault is not cleared, a second fault develops and a line-to-line short will occur. Bender’s insulation monitoring devices (IMDs) will give advanced notice of a first fault condition which allows for time to properly identify and clear the fault before a catastrophic issue arises. Bender offers a wide range of IMDs for virtually all size BESS, from small-scale deployments to commercial and industrial systems to large-scale, utility grade systems.

Earthed BESS

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Most BESS operate via an unearthed system design, however there are earthed installations that must have proper earth fault protection to operate safely. These systems can be earthed at the + or – pole of the DC (battery) circuit, or at the neutral connection point on the inverter. It is essential to detect gradual insulation deterioration or earth faults by means of residual currents. This allows issues to be detected and cleared at an early stage, before they trip a protection device and/or damage the batteries. Bender’s residual current monitors are able to detect low-level AC and DC earth faults to indicate minor issues before they become major issues, such as equipment fires or system shutdowns.

Fault location during operation

Minimising system downtime
Electrical issues can be detected and located while keeping the installation fully energised.

Reduced maintenance costs

Automatic fault location
Automatic fault location provides remote diagnostic tools which eliminates the need to have technicians on site in the event of a fault.

Indicator display

Increased safety
Earth-fault location at packs and modules minimises battery fire risk (with quick repair).

Automatic location of faults

Reduction of maintenance costs
Significant decrease in maintenance costs due to the accuracy of detection and decreased need for human interaction with the system.

Produktübersicht ISOMETER®
Produktübersicht Differenzstrom
Fachbeitrag Elektrische Sicherheit in Steuer- und Hilfsstromkreisen

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