Protection of LV/LV transformers, using Merlin Gerin circuit-breakers
From Electrical Installation Guide
Multi 9 circuit-breaker
| Transformer power rating (kVA) | Cricuit breaker | Size | ||
| 230/240 V 1-ph | 230/240 V 3-ph 400/415 V 1-ph | 400/415 V 3-ph | curve D or K | (A) |
| 0.05 | 0.09 | 0.16 | C60, NG125 | 0.5 |
| 0.11 | 0.18 | 0.32 | C60, NG125 | 1 |
| 0.21 | 0.36 | .063 | C60, NG125 | 2 |
| 0.33 | 0.58 | 1.0 | C60, NG125 | 3 |
| 0.67 | 1.2 | 2.0 | C60, NG125 | 6 |
| 1.1 | 1.8 | 3.2 | C60, C120, NG125 | 10 |
| 1.7 | 2.9 | 5.0 | C60, C120, NG125 | 16 |
| 2.1 | 3.6 | 6.3 | C60, C120, NG125 | 20 |
| 2.7 | 4.6 | 8.0 | C60, C120, NG125 | 25 |
| 3.3 | 5.8 | 10 | C60, C120, NG125 | 32 |
| 4.2 | 7.2 | 13 | C60, C120, NG125 | 40 |
| 5.3 | 9.2 | 16 | C60, C120, NC100, NG125 | 50 |
| 6.7 | 12 | 20 | C60, C120, NC100, NG125 | 63 |
| 8.3 | 14 | 25 | C120, NC100, NG125 | 80 |
| 11 | 18 | 32 | C120, NC100, NG125 | 100 |
| 13 | 23 | 40 | C120, NG125 | 125 |
Compact NS100…NS250 circuit-breakers with TM-D trip unit
| Transformer power rating (kVA) | Circuit-breaker | Trip unit | ||
| 230/240 V 1-ph | 230/240 V 3-ph 400/415 V 1-ph | 400/415 V 3-ph | ||
| 3 | 5...6 | 9...12 | NS100N/H/L | TN16D |
| 5 | 8...9 | 14...16 | NS100N/H/L | TM05D |
| 7...9 | 13...16 | 22...28 | NS100N/H/L | TN40D |
| 12...15 | 20...25 | 35...44 | NS100N/H/L | TN63D |
| 16...19 | 26...32 | 45...56 | NS100N/H/L | TN80D |
| 18...23 | 32...40 | 55...69 | NS160N/H/L | TN100D |
| 23...29 | 40...50 | 69...87 | NS160N/H/L | TN125D |
| 29...37 | 51...64 | 89...111 | NS250N/H/L | TN160D |
| 37...46 | 64...80 | 111...139 | NS250N/H/L | TN200D |
Compact NS100…NS1600 and Masterpact circuit-breakers with STR or Micrologic trip unit
| Transformer power rating (kVA) | Circuit-breaker | Trip unit | Setting Ir max | ||
| 230/240 V 1-ph | 230/240 V 3-ph 400/415 V 1-ph | 400/415 V 3-ph | |||
| 4...7 | 6...13 | 11...22 | NS100N/H/L | STR22SE 40 | 0.8 |
| 9...19 | 16...30 | 27...56 | NS100N/H/L | STR22SE 100 | 0.8 |
| 15...30 | 5...50 | 44...90 | NS160N/H/L | STR22SE 160 | 0.8 |
| 23...46 | 40...80 | 70...139 | NS250N/H/L | STR22SE 250 | 0.8 |
| 37...65 | 64...112 | 111...195 | NS400N/H | STR23SE / 53UE 400 | 0.7 |
| 37...55 | 64...95 | 111...166 | NS400L | STR23SE / 53UE 400 | 0.6 |
| 58...83 | 100...144 | 175...250 | NS630N/H/L | STR23SE / 53UE 630 | 0.6 |
| 58...150 | 100...250 | 175...436 | NS800N/H - NT08H1 | Micrologic 5.0/6.0/7.0 | 1 |
| 74...184 | 107...319 | 222...554 | NS800N/H - NT08H1 - NW08N1/H1 | Micrologic 5.0/6.0/7.0 | 1 |
| 90...230 | 159...398 | 277...693 | NS1000N/H - NT10H1 - NW10N1/H1 | Micrologic 5.0/6.0/7.0 | 1 |
| 115...288 | 200...498 | 346...866 | NS1250N/H - NT12H1 - NW12N1/H1 | Micrologic 5.0/6.0/7.0 | 1 |
| 147...368 | 256...640 | 443...1,108 | NS1600N/H - NT16H1 - NW16N1/H1 | Micrologic 5.0/6.0/7.0 | 1 |
| 184...460 | 320...800 | 554...1,385 | NW20N1/H1 | Micrologic 5.0/6.0/7.0 | 1 |
| 230...575 | 400...1, 000 | 690...1,730 | NW25N2/H3 | Micrologic 5.0/6.0/7.0 | 1 |
| 294...736 | 510...1,280 | 886...2,217 | NW32N2/H3 | Micrologic 5.0/6.0/7.0 | 1 |
