DEMA CPM 310 G User Manual page 46

Making of I>> Phase Overcurrent Protection Settings
c. To prevent pickup current reach the I>> threshold and cause an unwanted instantaneous
trip, I>> can be set to 7 I
d. According to the calculation above, do the following settings:
Making of Ie> Earth Overcurrent Protection Settings
e. It is assumed that earth current up to 0.25 I
value, the primary circuit will be broken in 1.0 s. Presuming those, I
calculated as follows:
f. According to the calculation above, do the following settings:
Making of Ie>> Earth Overcurrent Protection Settings
g. Presuming earth current equal to or higher than 0.75 I
I >> threshold value is calculated as below:
e
h. According to the calculation above, do the following settings:
6. All needed settings are done by now. Check all the settings and note them. CPM 310 G is ready
for commissioning. □
4 Actual pick-up current values can be checked on
practically. 4
rTR
�� ≫ = 7 × �� = 4.9 ��
������
Main Screen » Set » I>>
is considered to be normal. Over this
rTR
> = ( 15 �� 60 �� ⁄ ) ��
��
�� ����
Main Screen » Set » I >
e
≫ = ( 45 �� 60 �� ⁄ ) ��
��
�� ����
Main Screen » Set » I >>
e
MENU  Measurements  Max RMS Currents
- 46 -
��
> threshold value is
e
= 0.25 ��
����
is considered as earth fault,
rTR
= 0.75 ��
����
page.