Instruction manual

KRB-5377
40
5. OVERCURRENT RELEASE (OCR)
Options available for the type AR ACBs include a highly reliable, multi-functional overcurrent release (OCR) with a built-in 16-bit
microprocessor.
This OCR is supplied with power through a CT and main circuit current signals from current sensors. When the OCR detects a fault,
it sends a trip signal to the magnet hold trigger (MHT) or provides a trip indication or an alarm depending on the type of the fault.
The OCR uses the root mean square sensing for the long time delay (LT), pre-trip alarm (PTA, PTA2), and N-phase protection (NP)
functions. (When six times the CT rated primary current is exceeded.) If a harmonic current flows through the ACB continuously,
the root mean square sensing allows the ACB to operate normally.
The OCR is available in the type that follows:
z AGR-11BL,21BL,31BL L characteristic for general feeder (for works and transformer protection)
z AGR-21BR,31BR R characteristic for general feeder (3 characteristics conforming to IEC60255)
z AGR-21BS,22BS,31BS S characteristic for generator protection
5-1. Specifications
Specifications of the OCR are shown in Table 20,21.
Table 20 Specifications of type AGR-11B OCR (z: Standard, {: Optional, –: Not applicable)
Application For general feeder
Characteristic L
Type designation AGR-11BL-AL AGR-11BL-GL
Reference
section
Long time delay trip (LT)
Short time delay trip (ST)
Instantaneous trip (INST)
zz
Ground fault trip (GF) –
z
Protective
function
N-phase protection
{{
I
2
t ON/OFF (ST)
zz
Protection
characteristic
I
2
t ON/OFF (GF)
–
z
5-2-1.
Trip indication
Group indication LED and
contact output
zz
5-5-1.
Test function – – –
Control power supply
Not required Not required
3-3.