MAINTENANCE
Check M-RESTER periodically. Many cases of lightning are
ignored, and even lightning at a far distance often causes
inductive surges. We recommend that you check your M-
RESTER about twice a year, before and after the rainy
season. Check whenever you experience a strong lightning
occurrence.
Checking procedure is explained in the following:
■
CHECKING
WIRING
• Make sure that wiring is done as instructed in the con-
nection diagram.
• Make sure that the Ground terminal (3) is connected to
the metallic housing of protected equipment.
• Make sure that the Ground terminal (3) is grounded to
earth.
DISCHARGE FUNCTION
Remove all the wires connected to the M-RESTER and test
its discharge capability as follows:
• Apply 30V DC (MGD-24) or 70V DC (MGD-65) across
the following terminals with a resistor of approx. 50kW
in serial. Measure leakage current. (
≤
5mA standard)
Then apply 40V DC (MGD-24) or 80V DC (MGD-65) and
check that the discharging occurs. (≥100mA standard)
If a DC source is not available, check resistance across
these terminals on the high resistance range of multime-
ter, measured with positive potential at the terminal No.1
and 2 (infinite standard).
Terminals (1+) – (7–), (2+) – (8–)
• Apply 140V DC across the following terminals with a re-
sistor of approx. 1MW in serial. Measure leakage current.
(
≤
5mA standard)
Terminals (1) – (3), (2) – (3), (7) – (3), (8) – (3)
If a DC source is not available, check resistance across
these terminals on the high resistance range of multim-
eter (infinite standard).
• Check that discharging occurs across the same terminals
with a 500V DC megger. (Indicator of the megger reaches
over-scale.) Check also in the inverted polarity.
• If any of the above tests shows negative, replace the whole
MRESTER unit.
MGD-24 / MGD-65
5-2-55, Minamitsumori, Nishinari-ku, Osaka 557-0063 JAPAN
Phone: +81(6)6659-8201 Fax: +81(6)6659-8510 E-mail: [email protected]
EM-8211 Rev.4 P. 4 / 4
