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
occurence.
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 (G) is connected to
the metallic housing of protected equipment.
• Make sure that the Ground terminal (G) is grounded to
earth.
ALARM INDICATOR LED
• M-RESTER is designed to protect the equipment even
when subjected to a lightning surge exceeding its dis-
charge current capacity to certain extent. However, in
such a case, the insulation of its discharge element may
fail. When it happens, the fuse is blown and the green
LED on the front panel of M-RESTER turns off.
• Maximum surge voltage in this condition may be up to
800V.
• When the green LED is off despite that power is supplied,
replace the M-RESTER.
DISCHARGE FUNCTION
• Remove all wiring connected to M-RESTER and test its
discharge capability as follows:
• Check resistance across the following terminals (infinite
standard). Terminals (U) – (V), (U) – (G), (V) – (G)
• Check that discharging occurs across the following ter-
minals with a 500V DC megger. (Indicator of the megger
reaches over-scale.)
Terminals (U) – (V), (U) – (G), (V) – (G)
LEAKAGE CURRENT (between lines)
Apply supply voltage across the terminals (U) – (V) with
no load, and measure current at the terminal (U). (≤5mA
standard)
• If any of the above tests shows negative, replace the M-
RESTER.
MMA
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-8173 Rev.5 P. 3 / 3
