The Guide - MEM Technical Support

Thermal De-rating
Circuit Breakers

Thermal de-rating is primarily for environments which create a different ambient temperature. This could be due to temperature variants e.g. Scandinavia, where a re-rating factor is applied or the Middle East where a de-rating factor is applied, close proximity to other warmer operating products and small high IP rated enclosures may also increase the ambient temperature.

Memshield 2 - MCBs & RCBOs Types - B, C, D

Current Ratings (AMPS)	Device Rating (AMPS)
@40°C	@40°C	@55°C	@60°C
6	6.0	5.4	5.1
10	10.0	9.0	8.5
16	16.0	14.4	13.6
20	20.0	18.0	17.0
32	32.0	28.8	27.2
40	40.0	36.0	34.0
50	50.0	45.0	42.5
63	63.0	56.7	53.6
Memshield 2 MCBs are calibrated at an ambient temperature of 40°C. 50°C calibrated units are available without de-rating.

Memshield 2 - G Frame MCCBs Types - MGL, MGH, MGHAT

Current Ratings (AMPS)	Device Rating (AMPS)
@40°C	@20°C	@30°C	@40°C	@50°C	@60°C
16	19.2	17.6	16.0	14.4	13.0
20	24.0	22.0	20.0	18.0	16.6
32	38.4	35.2	32.0	28.8	26.5
40	48.0	44.0	40.0	36.0	33.2
50	60.0	55.0	50.0	45.0	41.2
63	75.6	69.3	63.0	56.7	52.0
80	96.0	88.0	80.0	72.0	66.0
100	120.0	110.0	100.0	90.0	83.0
125	150.0	137.5	125.0	112.5	104.0

Memshield 2 - Fixed Trip F Frame MCCBs Types - MFL, MFH

Current Ratings (AMPS)	Device Rating (AMPS)
@40°C	@20°C	@30°C	@40°C	@50°C	@60°C
16	19.4	17.8	16.0	14.9	13.6
20	24.2	22.2	20.0	18.6	17.0
32	38.7	35.5	32.0	29.8	27.2
40	48.4	44.4	40.0	37.2	34.0
50	60.5	55.5	50.0	46.5	42.5
63	76.2	69.9	63.0	58.6	53.6
80	96.8	88.8	80.0	74.4	68.0
100	121.0	111.0	100.0	93.0	85.0
125	151.3	138.8	125.0	116.3	106.3
160	193.6	177.6	160.0	148.8	136.0
200	242.0	222.0	200.0	186.0	170.0

Memshield 2 - Adjustable Trip F Frame MCCBs Types - MFLA, MFHA

Current Ratings (AMPS)	Device Rating (AMPS)
@40°C	@20°C	@30°C	@40°C	@50°C	@60°C
50	50.0	50.0	50.0	47.0	44.0
63	63.0	63.0	63.0	59.0	55.0
80	80.0	80.0	80.0	75.0	70.0
100	100.0	100.0	100.0	93.0	88.0
125	125.0	125.0	125.0	117.0	109.0
160	160.0	160.0	160.0	150.0	140.0
NOTE: Adjustable trip F Frame MCCBs require no ambient temp compensation between -5 to 40°C.

Memshield 2 - J & K Frame MCCBs Types - MJLA, MJHA, MKLA, MKHA

Current Ratings (AMPS)	Device Rating (AMPS)
@40°C	@20°C	@30°C	@40°C	@50°C	@60°C
160	160.0	160.0	160.0	150.0	141.0
200	200.0	200.0	200.0	188.0	176.0
250	250.0	250.0	250.0	235.0	220.0
320	320.0	320.0	320.0	304.0	288.0
400	400.0	400.0	400.0	380.0	360.0
NOTE: J & K Frame MCCBs require no ambient temp compensation between -5 to 40°C.

Memshield 2 - L Frame MCCBs Types - MLLA

Current Ratings (AMPS)	Device Rating (AMPS)
@40°C	@20°C	@30°C	@40°C	@50°C	@60°C
400	444.0	424.0	400.0	376.0	350.0
630	699.0	668.0	630.0	590.0	550.0
800	888.0	848.0	800.0	750.0	700.0

Memshield 2 - L Frame MCCBs Types - MLLS

Current Ratings (AMPS)	Device Rating (AMPS)
@40°C	@20°C	@30°C	@40°C	@50°C	@60°C
630	630.0	630.0	630.0	600.0	480.0
800	800.0	800.0	800.0	720.0	608.0

Memshield 2 - M & N Frame MCCBs Types - MMLS, MNLS (F&R Connection)

Current Ratings (AMPS)	Device Rating (AMPS)
@40°C	@20°C	@30°C	@40°C	@50°C	@60°C
1000	1000.0	1000.0	1000.0	1000.0	950.0
1250	1250.0	1250.0	1250.0	1125.0	950.0
1600	1600.0	1600.0	1600.0	1440.0	1216.0

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