NF800-REP datasheet(90/105 Pages) MITSUBISHI

90 / 105 page

Fig. 7.19 shows connection of high-speed fuses

for protection against thyristor breakdown that would

otherwise result in short-circuit flow from the AC sup-

ply side.

4. MCCBs for Lamp Mercury-Lamp Circuits

The ballasts (stabilizers) used in this type of lamp

cover a variety of types and characteristics. For 200V

applications (typical), choke-coil ballasts are used. For

100V applications a leakage-transformer ballast is

employed. Normal ballasts come in low power-factor

versions and high power-factor versions, with correc-

tion capacitors. More sophisticated types include the

constant-power (or constant-output) type, which main-

tains constant lamp current both in starting and nor-

mal running, and flickerless types, which minimize the

flicker attendant on the supply frequency.

In selecting an MCCB where normal (high or low

PF) ballasts are to be used, the determining factor is

the starting current, which is about 170% of the stable

running current. In the cases of constant-power or

flickerless types, the determining factor is the normal

running current, which is higher than the starting cur-

rent. For MCCB selection, the latter types can be re-

garded as lighting and heating general loads, as pre-

viously discussed.

For selection of MCCBs for regular ballasts, the

170% starting current is assumed to endure for a

maximum of 5 minutes. MCCBs of 100A or less frame

size have a tripping value very close to rating for over-

loads of duration of this order, so that the MCCB rat-

ing should be the nearest standard value above 170%

of the stable running current. MCCBs of above 100A

frame size can handle a current of around 120% of

the rating for 5 minutes without tripping; thus the near-

est standard MCCB rating above

1.2

1.7 = 1.4 times the

stable-running current of the lamp load is the suitable

protector.

As an example, consider MCCB selection for 10

units of 100W, 100V, 50Hz general-purpose high

power-factor mercury lamps. The stable-running cur-

rent per lamp is 1.35A. Thus:

1.35 x 10 x 1.7 = 23A, and the selection becomes

NF30-SP, 30A rated.

NF800-REP Datasheet(PDF) 90 Page - Mitsubishi Electric Semiconductor

NF800-REP Datasheet(HTML) 90 Page - Mitsubishi Electric Semiconductor

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