GE B90 User Manual

2-16 B90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
SPECIFICATIONS CHAPTER 2: PRODUCT DESCRIPTION
2
2.5.1 Protection elements
The operating times include the activation time of a trip rated form-A output contact unless otherwise indicated. FlexLogic
operands of a given element are 4 ms faster. Take this into account when using FlexLogic to interconnect with other
protection or control elements of the relay, building FlexLogic equations, or interfacing with other intelligent electronic
devices (IEDs) or power system devices via communications or different output contacts. If not specified, the operate times
given here are for a 60 Hz system at nominal system frequency. Operate times for a 50 Hz system are 1.2 times longer.
BUS DIFFERENTIAL (87B)
Pickup level: 0.050 to 6.000 pu in steps of 0.001
Low slope: 15 to 100% in steps of 1
High slope: 50 to 100% in steps of 1
Low breakpoint: 1.00 to 30.00 pu in steps of 0.01
High breakpoint: 1.00 to 30.00 pu in steps of 0.01
High set level: 0.10 to 99.99 pu in steps of 0.01
Dropout level: 97 to 98% of pickup
Level accuracy:
0.1 to 2.0 × CT rating: ±0.5% of reading or ±1% of rated (whichever is greater) for six circuits or less in the zone
>2.0 × CT rating ±1.5% of reading of the maximum circuit current
Operating time: one power system cycle (typical)
Number of zones: 1 or 6 (option)
Max number of inputs: 8, 16, or 24 (option)
CT TROUBLE
Responding to: Differential current
Pickup level: 0.020 to 2.000 pu in steps of 0.001
Pickup delay: 1.0 to 60.0 sec. in steps of 0.1
Timer accuracy: ±3% of operate time or ±1/4 cycle (whichever is greater)
Availability: one per zone of protection
ISOLATOR MONITORING
Responding to: Both normally-open and normally-closed auxiliary contacts
Asserting: Isolator Position, Isolator Alarm, Block Switching
Alarm pickup delay: 0.00 to 120.00 s in steps of 0.05
Timer accuracy: ±3% of operate time or ±1/4 cycle (whichever is greater)
TIME OVERCURRENT
Pickup level: 0.020 to 30.000 pu in steps of 0.001
Dropout level: 97 to 98% of pickup
Level accuracy:
0.1 to 2.0 × CT 0.5% of reading or 1% of nominal (whichever is greater)
above 2.0 × CT 1.5% of reading
Curve shapes: IEEE Moderately/Very/Extremely Inverse; IEC (and BS) A/B/C and Short Inverse; GE IAC Inverse,
Short/Very/Extremely Inverse; I
2
t; FlexCurves™ (programmable); Definite Time (0.01 s base
curve)
TD multiplier: 0.00 to 600.00 in steps of 0.01
Reset type: Instantaneous or Timed (per IEEE)
Curve timing accuracy at 1.03 to 20 x pickup:
±3.5% of operate time or ±1/2 cycle (whichever is greater) from pickup to operate
INSTANTANEOUS OVERCURRENT
Pickup level: 0.020 to 30.000 pu in steps of 0.001
Dropout level: 97 to 98% of pickup
Level accuracy:
0.1 to 2.0 × CT 0.5% of reading or 1% of nominal (whichever is greater)
above 2.0 × CT 1.5% of reading

GE B90 Specifications

General

Brand	GE
Model	B90
Category	Relays
Language	English