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Wire Size: The wire size for the cables between the mains and arrester terminals should be
6 AWG to 2/0 AWG, 2 AWG is typically used. Connect the Ground wire to the lug
provided inside the protector cabinet. Connect the Neutral wire to the terminal marked
"Neutral" on the metallic circuit board. Connect the 3 Phase wires to the isolated
terminals marked "Phase A", "Phase B", and "Phase C" in any sequence.
Remote Sensing Circuit: The terminal blocks on top of the relay bracket at either end
provide connections to the unpowered sensing relay contacts. If a closing of relay
contacts is desired when an arrester module becomes defective or is no longer
providing adequate protection, connect sensing wires to terminals 1 and 2. If an
opening of relay contacts is desired, connect sensing wires to terminals 2 and 3. See
Figure 2 for details.
III. THEORY OF OPERATION
The purpose of the Joslyn AC Surge Protector, Model 1456-85-L, is to clamp the voltage
whenever instantaneous (surge) voltage on any phase exceeds a level of approximately 500
volts peak. The protector responds in nanoseconds, and automatically restores itself to
normal condition after termination of the surge condition. No power-follow occurs and the
disturbance to the line voltage is minimal.
Each phase of the protector has four protector modules, two connected L-N, two connected
L-G, and two monitoring circuits. Refer to connection diagram of Figure 2.
Each protector module consists of several Metal Oxide Varistors (MOV) connected in
parallel. Each MOV has its own fuse. The fuse will blow before the maximum surge current
rating of the MOV is exceeded. The fuses also help to balance the current distribution
among the MOV's.
Each phase of the protector has a monitoring circuit with two indicator lights on the cover of
the protector enclosure. One light shows that the Line to Neutral (L-N) protection is
operating and the other shows the Line to Ground (L-G) protection is operating.
Each phase also has two relays that are sensing the presence of L-N and L-G protection of
the modules. The 2 individual unpowered sets of relay contacts are presented on two
terminal strips above and below the relays; these provide connection points for remote
monitoring/external alarming. Terminals 1 and 2 on the terminal strip provide connections to
the open contacts of all relays are in parallel. Terminals 2 and 3 provide connections to the
closed contacts of all relays in series.
MAG/MNL145685L(NC)
4
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