Application Notes; Protection Schemes; Current Differential Protection - Toshiba GRL150-100 Series Instruction Manual

2. Application Notes

2.1 Protection schemes

The GRL150 provides the following protection schemes:
• Segregated-phase current differential protection
• Phase fault overcurrent protection
• Earth fault protection
• Sensitive earth fault protection
• Phase undercurrent protection
• Thermal overload protection
• Broken conductor protection
• Circuit breaker failure protection
• Cold load protection

2.2 Current Differential Protection

GRL150 is applied as a segregated-phase current differential protection for use with pilot wire or
direct fibre optic communication as shown in Figure 2.2.1.
For pilot wire communication, GRL150 can be applied to circuits up to 8 km in length for
0.91mmφ and provides built-in 5kV and optional 20kV isolation. For direct fibre optic
communication, GRL150 can be applied to circuits up to 20km in length. The fibre optic cable is
single-mode (SM) 10/125μm type.
TX
RX
GRL150
(a) Fibre optic(SM)
TB3-A16
-A17
GRL150
(b) Pilot wire
Figure 2.2.1 Current Differential Protection
⎯ 10 ⎯
6 F 2 S 0 8 2 8
RX
TX
GRL150
TB3-A16
-A17
GRL150