418 Electrical Power Systems Technology
motor, and the type of power distribution (single-phase or three-phase).
For example, a heater with an H37 code number is used with a motor that
has a full-load current of 18.6 to 21.1 amperes.
Table 15-3 is used with bimetallic overload relays. They are selected
in the same manner as melting-alloy relays. However, this table shows the
trip amperes of the heater. A heater with a K53 code number has a 13.9
trip-ampere rating. Thus, a current in excess of 13.9 amperes would cause
the heater element to trip. This would open the motor branch circuit by
removing the power from the motor.
Table 15-2. Melting Allow Devices
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Table 26142
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Full Load Heater Full Load Heater Full Load Heater
Motor Amps. Code Motor Amps. Code Motor Amps. Code
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12.6 - 14.5 H33 21.2 - 22.2 H38 34.6 - 38.9 H43
14.6 - 16.0 H34 22.3 - 23.6 H39 39.0 - 44.7 H44
16.1 - 16.9 H35 23.7 - 26.2 H40 44.8 - 48.8 H45
17.0 - 18.5 H36 26.3 - 30.1 H41 48.9 - 54.2 H46
18.6 - 21.1 H37 30.2 - 34.5 H42 54.3 - 60.0 H48
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Table 15-3. Bimetallic Devices
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Table 62K
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Trip Heater Trip Heater Trip Heater
Amperes Code Amperes Code Amperes Code
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1.95 K21 5.59 K36 17.0 K56
2.12 K22 6.39 K37 18.3 K57
2.31 K23 6.88 K39 19.8 K58
2.49 K24 7.78 K41 21.0 K60
2.75 K26 8.42 K42 22.5 K61
3.05 K27 9.54 K43 24.1 K62
3.29 K28 10.1 K49 25.7 K63
3.69 K29 11.5 K50 28.3 K64
4.01 K31 12.6 K52 31.1 K67
4.32 K32 13.9 K53 34.6 K68
4.77 K33 15.1 K54
5.14 K34 16.0 K55
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