GE Industrial Solutions EntelliGuard TU Trip Units - Manual (Page 25)

DEH-4567B EntelliGuard TU Trip Units: UL/ANSI Models
Protection
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Figure 2-5: Restrained ZSI Settings
ZSI Option
Two Zone- Selective-Interlocking options may be
purchased with each trip. Option "Z" or option "T". Option Z
allows the user access to short time or ground fault ZSI.
The user may enable or disable either or both. The "T"
option adds Instantaneous ZSI capability. Instantaneous
ZSI may be enabled or disabled by the user at any time.
Use of the short time or GF ZSI in a CB requires that the
user set two different delay and slope bands for ground
fault or short time depending on which he has enabled.
In Power Break II and Spectra MicroEntelliGuard Circuit
Breakers the "T" option only enables instantaneous ZSI
as an output to interlock with upstream circuit breakers
such as a GE WavePro, AK, AKR, Conversion Kits or new
EntelliGuard G (ANSI or UL489). The T option requires 24
VDC external power. The T option does not modify IOC
timing on PowerBreak I, PowerBreak II and Spectra
MicroEntelliGuard circuit breakers.
The upstream breaker uses the ST ZSI and/or GF ZSI delay
bands and slope, and/or transition to a delay
Instantaneous if it receives a downstream ZSI signal.
The desired ZSI (ST and/or GF and/or Instantaneous) must
be selected in order for the downstream breaker to issue a
ZSI signal, and the upstream breaker to act upon this
signal. If the ZSI setting is set to OFF no ZSI output signal is
generated.
The ST ZSI Delay Bands are independent and have the
same bands available. Slope settings may also be
interlocked.
The GF ZSI Delay Bands are independent and have the
same bands available. Slope settings may also be
interlocked.