Eaton Electrical CA03310002E Trip Times, Utilization Categories, Category Typical Application

12	NEMA Contactors & Starters
	IT. Electro-Mechanical

September 2003

Technical Data and Specifications

Electrical Life — AC-1, AC-2, AC-3 and AC-4 Utilization Categories

Table 8. Utilization Categories

The International Electrotechnical Commission (IEC) has developed utilization categories for contactors and auxiliary contacts. The IEC utilization categories are used to define the type of electrical load for estimating electrical life, and do not imply the devices are IEC rated.

Category

Typical Application

AC-1

AC-2

AC-3

AC-4

Non-inductive or slightly inductive loads: Resistance furnaces, heating.

Slip-ring motors: Starting and stopping of running motors

Squirrel cage motors: Starting, switching off motors during running (motors in most industrial applications typically fall into this category).

Squirrel cage motors: Starting, plugging , inching (very few applications in industry are totally AC-4).

Plugging is stopping or reversing the motor rapidly by reversing the connections while the motor is running.

Inching or jogging is energizing the motor once or repeatedly for short durations to obtain small movements of the motor driven load.

Life Load Curves — Eaton’s Cutler- Hammer IT. Electro-Mechanical Series NEMA contactors have been designed and manufactured for superior life per- formance. All testing has been based on requirements as found in IEC

60947-4-1 and conducted by us. When selecting a contactor, the specifier must give attention to the specific load, utilization category and the required electrical life. For a definition of Utilization Categories, see Table 8 above.

Note: AC-3 tests are conducted at rated device currents and AC-4 tests are con- ducted at six-times rated device currents. All tests have been run at 460V, 60 Hz.

Actual application life may vary, depending on environmental condi- tions and application duty cycle.

Contactor Choice —

■Decide what utilization category the application is and choose the appropriate curve from Figure 1 or Figure 2.

■Locate the intersection of the life- load curve with the operational cur- rent (le) of the application, as found on the horizontal axis.

■Read the estimated contact life along the vertical axis in number of operations.

Trip Times

									NEMA Size
	10,000,000		00 0		1			2	3 4		5
Operations	1,000,000
	100,000
	10,000
	1					9			18	27	45	90	135	270
						10						100		1000
Note: Preliminary data.							Operational Current
Figure 1. Electrical Life — AC-3 Utilization Category
		00 0	1	2	3 4	5			NEMA Size
	10,000,000
Operations	1,000,000
	100,000
	10,000
	1					9			18	27	45	90	135	270
						10						100		1000
Note: Preliminary data.							Operational Current

Figure 2. Electrical Life — AC-4 Utilization Category

1000.0

100.0
(Seconds)	10.0		5
Time			3
Trip
			6
			1
			4
	1.0	2

0.1	2	3	4	5	6	7	8	9	10
1

Multiples of FLA

1Trip Class 10 Cold

2Trip Class 10 Hot

3Trip Class 20 Cold

4Trip Class 20 Hot

5Trip Class 30 Cold

6Trip Class 30 Hot

Figure 3. Class 10, 20 and 30 Trip Curves

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