Battery Energy Storage Systems (BESS)


bess in the field

Ungrounded BESS

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.


Grounded Battery Energy Storage Systems

Grounded BESS

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.


Energy Storage Systems Flyer
Product overview ISOMETER®
Product overview Residual current monitoring
Technical paper Insulation fault location - Planning and set up in the solar charging station at the University of Applied Sciences Bingen
Technical paper Electrical safety in control and auxiliary circuits

Recommended solutions for ground-fault detection (ungrounded systems):


Recommended solutions for ground-fault detection and location (grounded systems):


Recommended solutions for ground-fault location:


Accessories:

NEC 706.30(D)

For BESS greater than 100V between conductors, circuits can be ungrounded if a ground fault detector is installed.

UL 9540:2020 Section 14.8

For BESS greater than 100V between conductors, circuits can be ungrounded if ground fault detector is installed.