Electrical Safety for Battery Energy Storage Systems (BESS)

Why Choose a Grounded or Ungrounded Solution for 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 are properly monitored to maintain the benefits.

BESS most commonly operate as ungrounded systems, which mean all line conductors are intentionally isolated from ground. Although these systems can continue to operate with a single ground 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 large-scale, utility grade systems.

Most BESS operate via an ungrounded system design, however there are grounded installations that must have proper ground fault protection to operate safely. These systems can be grounded on the + or – battery line, or at the neutral connection point on the inverter. It is critical to monitor for ground faults at low leakage current levels to detect and clear issues 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 grounds faults to indicate minor issues before they become major issues, such as equipment fires or system shut downs.