BuyLog Flippingbook MAR 2024

MOLDED CASE CIRCUIT BREAKERS, BUYLOG SECTION 6

6-10

— Formula circuit breakers for power distribution Thermal-magnetic trip unit

The thermal-magnetic trip units TMF, with fixed thermal and magnetic threshold, are generally used in power distribution plants. They allow protection against overloads due to the thermal device and protection against short circuit due to the magnetic device:

• Thermal protection (L): fixed threshold I1= 1x1In, with long inverse time trip curve • Magnetic protection (I): fixed threshold I3= 10xIn, with instantaneous trip curve

Fixed thermal-magnetic trip unit TMF An example with FORMULA A2 In=125 A

Thermal protection symbol

Magnetic protection symbol

Thermal protection value

Magnetic protection value

— FORMULA A1 with trip unit TMF

TMF

In (A) 15 20 25 30 40 50 60 70 80 90 100 Neutral (A) — 100% 15 20 25 30 40 50 60 70 80 90 100 400 500 600 700 800 900 1000 Neutral (A) — 100% 300 300 300 600 400 500 600 700 800 900 1000 I3 (A) 300 1 300 1 300 1 300 1

I1= 1xIn

I3= 10xIn

1 Single- and two-pole versions have an I3 (3) of 400.

— FORMULA A2 with trip unit TMF

TMF

In (A) 125 150 175 200 225 250 Neutral (A) — 100% 125 150 175 200 225 250 I3 (A) 1250 1500 1750 2000 2250 2500 Neutral (A) — 100% 1250 1500 1750 2000 2250 2500

I1= 1xIn

I3= 10xIn