GE EntelliGuard G - Locks and Interlocks; Circuit Breaker Front Panel Locking

DET-653C EntelliGuard
®
G Circuit Breaker Application Guide
24-May-12 Section 3. EntelliGuard
®
TU Trip Unit System
©2012 General Electric All Rights Reserved
16
Long Time Protection
The EntelliGuard TU offers two different shapes for Long
Time protection curves. Each type of curve is available with
22 different time delays. The shapes may be described as
thermal type I
2
t characteristics and fuse shaped I
4
t lines.
The nominal Long Time pickup is computed from the trip
rating plug value (In) multiplied by the Long Time pickup
setting. Long Time pickup setting multipliers are user
settings and may range from 0.5 to 1.0 in increments of 0.05.
The actual Long Time pickup is 112% of the nominal setting
(Ir). 112% is to compensate for the Long Time Pickup
Tolerance of ±10% that is drawing as “actual value/1+
tolerance)”. For a nominal 1000A Long Time pickup, the
actual trip setting is 1120A, drawn as a vertical band
between 1120/1.1 and 1120/0.9, or 1018A and 1244A.
Thermal Long Time Overcurrent
The thermal I
2
t shape is similar to the typical curve of a
thermal magnetic circuit breaker and matches the shape of
many overcurrent devices used in industry today. The typical
shape and range of settings may be seen in Figure 3.3. The
range of time delays is shown in Table 3.5 at various
multiples of nominal (100%) current setting. Drawn bands
also include a mechanical constant time to account for
circuit breaker operating and clearing time, which causes
the slight widening of the band evident at the lower (right)
end of the faster (lower) bands.
Figure 3.3. Thermal Characteristic: Maximum and
Minimum Long Time Delay Bands for a 1000A Long Time
Pickup
Breaker Type
TCC
EntelliGuard G:
DES-090
WavePro, PBII, PBI, AK, AKR, Conv Kits
DES-095