Utilization categories
In electrical engineering utilization categories are defined by IEC standards[1] and indicate the type of electrical load and duty cycle of the loads to ease selection of contactors and relays.
| Utilization Category | Type of Application[2] |
|---|---|
| AC-1 | Non-inductive or slightly inductive loads, example: resistive furnaces, heaters |
| AC-2 | Slip-ring motors: switching off |
| AC-3 | Squirrel-cage motors: starting, switches off motors during running time |
| AC-4 | Squirrel-cage motors: starting, plugging, inching |
| AC-5a | Switching of discharge lamps |
| AC-5b | Switching of incandescent lamps |
| AC-6a | Switching of transformers |
| AC-6b | Switching of capacitor banks |
| AC-7a | Slightly inductive loads in household appliances: examples: mixers, blenders |
| AC-7b | Motor-loads for household appliances: examples: fans, central vacuum |
| AC-8a | Hermetic refrigerant compressor motor control with manual resetting overloads |
| AC-8b | Hermetic refrigerant compressor motor control with automatic resetting overloads |
| AC-12 | Control of resistive loads and solid state loads with opto-coupler isolation |
| AC-13 | Control of solid state loads with transformer isolation |
| AC-14 | Control of small electromagnetic loads |
| AC-15 | Control of A.C. electromagnetic loads |
| AC-20 | Connecting and disconnecting under no-load conditions |
| AC-21 | Switching of resistive loads, including moderate overloads |
| AC-22 | Switching of mixed resistive and inductive loads, including moderate overloads |
| AC-23 | Switching of motor loads or other highly inductive loads |
| A | Protection of circuits, with no rated short-time withstand current |
| B | Protection of circuits, with a rated short-time withstand current |
| DC-1 | Non Inductive or slightly inductive loads, resistance furnaces, heaters |
| DC-3 | Shunt-motors, starting, plugging(1), inching(2), dynamic braking of motors |
| DC-5 | Series-motors, starting, plugging(1), inching(2), dynamic braking of motors |
| DC-6 | Switching of incandescent lamps |
| DC-12 | Control of resistive loads and solid state loads with opto-coupler isolation |
| DC-13 | Control of D.C. electromagnetics |
| DC-14 | Control of D.C. electromagnetic loads having economy resistors in the circuit |
| DC-20 | Connecting and disconnecting under no-load conditions |
| DC-21 | Switching of resistive loads, including moderate overloads |
| DC-22 | Switching of mixed resistive and inductive loads, including moderate overloads (i.e. shunt motors) |
| DC-23 | Switching of highly inductive loads (i.e. series motors) |
References
- ↑ IEC 60947 Standards for low-voltage switchgear and controlgear
- ↑ http://www.eecontrols.com/documents/Pages21-30.pdf
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