MAT2
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-8149 Rev.6 P. 3 / 6
CONNECTION PROCEDURE
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INSTALLING CIRCUIT BREAKERS
The MAT2 incorporates a thermal breaker which separates the discharge element from the power line upon detecting the
increased leakage current by the element’s gradual degradation.
However, in rare cases, when the MAT2 is hit by an extremely strong lightning which exceeds the MAT2’s designed induced
surge capacity, the discharge element may be burned out and short-circuited at a burst without the thermal breaker being
able to separate it safely from the line.
Install a circuit breaker at the power source side of the surge protector as a backup protection. The example below shows a
three-phase/4-wire configuration. Molded-case circuit breakers (MCCB), residual current circuit breaker (RCD) or current-
limiting fuses (slow-blow type only) can be used.
*
1. The circuit breaker must be installed.
Molded-case circuit breaker (MCCB) or residual current circuit breaker with overcurrent protection (RCD) can be used.
The rated interrupting capacity of the circuit breaker must be greater than the highest amount of current that could be available in the circuit.
Install MCCB (rated current 20
–
30A) that has element for each phase.
Or RCD with time-delay overcurrent protection is recommended. Recommended sensitivity current rating: 30mA
*
2. Cable length between the branch point and the earthing: 0.5 meters or less recommended
*
3. The protected device's metal enclosure must be cross-wired to the earth terminal of the MAT2. If the protected device has no earth terminal,
earth only the MAT2.
*
4. In order to protect an electronic circuit such as measuring equipment or communication equipment, we recommend to use surge protectors
which have serial impedance incorporated such as M-System's models MAX, MMA, MAH.
*
1
*
3
E
D
E
B
*
4
1) : Protective device of the switchgear
2) : Circuit breaker
3) : Main earth terminal or busbar
4) : MAT2
5) : Earth conductor
5)a and/or 5)b
6) : Protected device
E
B
:
Main's earth electrode
E
D
:
Switchgear's earth electrode
1)
2)
3)
6)
5)a
5)b
N
*
2
L2
L1
L3
PE
N
Residual
Current
Circuit
Breaker
4)
2
1
PE
N
3
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USING AN EARTH LEAKAGE CIRCUIT BREAKER
RCD with protection from nuisance tripping against transit voltages type or time-delay overcurrent protection type is recom-
mended for use with surge protectors.
■
CIRCUIT BREAKER REQUIREMENTS
Additional requirements are listed below:
• When the alarm output of the MAT2 should be used, choose also a circuit breaker with an alarm output. Configure a logical
addition sequence so that the alarm trips when both or either of the MAT2 or the breaker alarm trips.
• Recommended rating of a current-limiting fuse: Rated current 30 A, I
2
t value 5000 A
2
s minimum. Current-limiting fuses
have no alarm and thus are not recommended when the MAT2 is with the alarm output.
