Mitsubishi Electric NF250-SEV Instruction Manual page 10

2 400/800 A frame

(1) Send AC power to the MDU Breaker main unit from a 3-phase power supply or 1-phase power supply.

When using a 1-phase power supply, do so from two poles in series.

Current adjustable resister

(2) Each operating current can be confirmed by checking the LEDs on the front of the MDU Breaker main unit.

70% LED (green) ･･･････････ Acceptable when it begins to stay ON within 60% to 80% of current setting.

PAL LED (yellow) ･･････････ With lp = 0.7 × lr, acceptable when it starts to blink every 0.5 seconds within 60% to 80% of current setting.

OVER LED (red) ････････････ Acceptable when it begins to stay ON at 105% to 125% of current setting.

(3) The long time delay and pre-alarm operating times can be confirmed by sending a current equivalent to 200% of current setting.

However, if a current exceeding current setting is sent prior to this test, the operating time will shorten and the first measurement will be invalid.

Tripping the MDU Breaker main unit will reset the tripping circuit, allowing the following operating time to be measured correctly.

200% current

70% LED (green)

PAL LED (yellow)

Pre-alarm operating time

OVER LED (red)

Acceptable if measured operating time is within range below.

Measurement item

Pre-alarm operating time

Long time delay operating time

Current adjustable resister

Begins to stay ON

Long time delay operating time

TL = 12 s

4.8 to 7.2 s

9.6 to 14.4 s

Trip

TL = 60 s

TL = 100 s

24 to 36 s

40 to 60 s

48 to 72 s

80 to 120 s

9

TL = 150 s

60 to 90 s

120 to 180 s