Capstone Turbine Corporation • 16640 Stagg Street • Van Nuys • CA 91406 • USA
Installation Guide: Capstone C1000S/C800S/C600S with C1000 Series Controller
480064 Rev C (December 2018) Page 68 of 122
Capstone reserves the right to change or modify, without notice, the design, specifications, and/or contents of this document without
incurring any obligation either with respect to equipment previously sold or in the process of construction.
7.2.2. Grounding the Microturbine Neutral
GROUNDING REQUIREMENT. A solid earth ground — 5 Ω or less — of the
microturbine neutral is MANDATORY for successful operation. Any high-
impedance grounding scheme MUST BE APPROVED BY CAPSTONE PRIOR
TO COMMISSIONING. Failure to observe this caution may result in equipment
damage.
All microturbine installations must have the neutral wire correctly grounded for
proper operation. Failure to correctly ground the neutral — i.e. no neutral-to-
ground connection or more than one neutral-to-ground connection — can
damage the system.
A high impedance or resistive ground is not necessary due to the very low fault
current contribution of the microturbine — approximately 2x nominal current —
and should be avoided when possible. If a high impedance ground is required,
a modification to the microturbine and additional external surge protection
equipment must be approved by Capstone Applications Engineering and will be
supplied by the installer.
It is recommended that neutral wire(s) only ground in a single location, unless local code requires
more than one connection. For example, it is sometimes required by local code to ground the
neutral before the conductor leaves one building and travels into another, in case the neutral is
broken during earthmoving activities. In the case of multiple grounding points, these grounding
points should be at equivalent potentials; otherwise circulating currents can occur and provide a
poor reference for operation. See Figure 26 for proper neutral-to-ground connection.
For Grid Connect installations, the required location of the neutral-to-ground connection is at the
utility service panel or the utility service transformer. A neutral-to-ground connection is often
already present at the Wye utility service transformer.
For Stand Alone and Dual Mode installations, the recommended location of the neutral-to-ground
connection is at the microturbine service panel. Use of four-pole breakers may necessitate
multiple neutral-to-ground connections, and more information is provided on this subject in
Section 7.7.
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