Phase Current - GE t60 Instruction Manual

5 SETTINGS
a) MAIN MENU
PATH: SETTINGS GROUPED ELEMENTS

PHASE CURRENT

MESSAGE
MESSAGE
MESSAGE
MESSAGE
The Phase Current elements can be used for tripping, alarming, or other functions. The actual number of elements
depends on the number of current banks.
b) INVERSE TOC CHARACTERISTICS
The inverse time overcurrent curves used by the TOC (time overcurrent) Current Elements are the IEEE, IEC, GE Type
2
IAC, and I t standard curve shapes. This allows for simplified coordination with downstream devices. If however, none of
these curve shapes is adequate, FlexCurves™ may be used to customize the inverse time curve characteristics. The Defi-
nite Time curve is also an option that may be appropriate if only simple protection is required.
Table 5–11: OVERCURRENT CURVE TYPES
IEEE
IEEE Extremely Inv.
IEEE Very Inverse
IEEE Moderately Inv.
A time dial multiplier setting allows selection of a multiple of the base curve shape (where the time dial multiplier = 1) with
the curve shape ( ) setting. Unlike the electromechanical time dial equivalent, operate times are directly proportional
CURVE
to the time multiplier (
TD MULTIPLIER
or base curve values. Setting the multiplier to zero results in an instantaneous response to all current levels above pickup.
Time overcurrent time calculations are made with an internal "energy capacity" memory variable. When this variable indi-
cates that the energy capacity has reached 100%, a time overcurrent element will operate. If less than 100% energy capac-
ity is accumulated in this variable and the current falls below the dropout threshold of 97 to 98% of the pickup value, the
variable must be reduced. Two methods of this resetting operation are available: "Instantaneous" and "Timed". The Instan-
taneous selection is intended for applications with other relays, such as most static relays, which set the energy capacity
directly to zero when the current falls below the reset threshold. The Timed selection can be used where the relay must
coordinate with electromechanical relays. With this setting, the energy capacity variable is decremented according to the
equation provided.
Graphs of standard time-current curves on 11" × 17" log-log graph paper are available upon request from
the GE Multilin literature department. The original files are also available in PDF format on the UR Software
Installation CD and the GE Multilin website at http://www.GEindustrial.com/multilin.
NOTE
GE Multilin
SETTING GROUP 1(6)
PHASE TOC1
↓
PHASE TOC6
PHASE IOC1
↓
PHASE IOC8
PHASE
DIRECTIONAL 1
IEC
IEC Curve A (BS142)
IEC Curve B (BS142)
IEC Curve C (BS142)
IEC Short Inverse
) setting value. For example, all times for a multiplier of 10 are 10 times the multiplier 1
T60 Transformer Management Relay
PHASE CURRENT
See page 5–86.
See page 5–88.
See page 5–89.
GE TYPE IAC
IAC Extremely Inv.
IAC Very Inverse
IAC Inverse
IAC Short Inverse
5.5 GROUPED ELEMENTS
5.5.4 PHASE CURRENT
OTHER
2
I t
FlexCurves™ A, B, C, and D
Recloser Curves
Definite Time
5-81
5