Toshiba GRT100 Series Instruction Manual page 127

6.5.1.7 Inverse time overcurrent elements OCI, EFI
The testing circuit is shown in Figure 6.5.11.
Single-phase
current
source

DC
power

supply
Start
Time
counter
Stop
OV
Figure 6.5.11 Testing OCI and EFI (Model 100s, 200s)
One of the four inverse time characteristics can be set, and the output signal numbers are as
follows:
Element
1OCI, 2OCI, 3OCI
1EFI, 2EFI, 3EFI
Fix the time characteristic to test by setting the OCI or EFI on the "OC" screen.
"Setting (change)" sub-menu  "Protection" screen  "Trip" screen  "Protection element"
screen  "OC" screen
The testing procedure is as follows:
 Press 4 (= Logic circuit) on the "Test" sub-menu screen to display the "Logic circuit" screen.
 Enter a signal number to observe the OCI or EFI output at monitoring jack A and press the
ENTER key.
 Apply a test current and measure the operating time. The magnitude of the test current should
be between 1.2  I s to 20  I s , where I s = (CT secondary rated current) × (OCI or EFI current
setting).
 Calculate the theoretical operating time using the characteristic equations shown in Section
2.11.4. Check that the measured operating time is within the error mentioned below.
Accuracy: Standard, Very and Long-time inverse: IEC 60255-3 class 5
Signal number
50, 56, 62
73, 76, 79
Extremely inverse: IEC 60255-3 class 7.5
 126 
GRT100
TB 1
-1
A
I a
- 2
- 7
I N
- 8
Monitoring
jack
TB 4 - A16
- A17
E
6 F 2 S 0 7 8 9
A
0V