Unable to Recharge the prepaid meter

Solution: Connectivity Check: Confirm the meter is successfully communicating with the server. Serial Number Verification (SmartComm): Access the SmartComm Customer Master and ensure the serial number recorded matches the physical serial number of the connected meter. Duplicate Configuration Check: Verify that no two meters are incorrectly configured with the exact same serial number in the system.

Email Configuration SMTP Details Outlook

Solution: SMTP Host/Server Name: For Outlook.com: smtp-mail.outlook.com For Office 365/Microsoft 365: smtp.office365.com SMTP Port:587 (recommended) Encryption Method: STARTTLS Authentication: Your email account needs to be authenticated, so enable login or use the ""My outgoing server (SMTP) requires authentication"" option in your email client. Username: Your full Outlook email address (e.g., yourname@outlook.com or yourname@domain.com) Password: Blank

Email Configuration App Password creation for Gmail account

Reason - Gmail will work only with a secure encrypted app password Solution: Go to your Google Account settings. Navigate to the Security tab. If you don't have it enabled, turn on Two-Step Verification. Find and click on App passwords. Select an app name (like ""SMTP"" or ""Mail Client"") and click Generate. Copy the generated 16-character password and use it in your mail client's password field instead of your main Gmail password.

Email Configuration SMTP Details Gmail

Solution: Gmail SMTP Settings SMTP Server: smtp.gmail.com Port: 587: (requires STARTTLS/TLS) 465: (requires SSL) Authentication: Required Username: Your full Gmail address (e.g., user@gmail.com) Password: An App Password generated from your Google Account security settings Security/Connection: TLS or SSL, depending on the port chosen

Transfer existing sensor to a different gateway

Reason - Loss of old data stored under device id created Solution: To prevent data loss, edit the sensor and use the "Move to Gateway" option to transfer the sensor to a different gateway.

Asset list is not available in the filter

Reason - The asset is not assigned to the organization Solution: Check the asset selection settings in organization settings

Reason - Sensor/gateway limit exceeded Solution: Check license information for sensor/gateway limit

Cannot change the ip address of gateway

Reason - The ip address should is not available Solution: 1. if company network is being used check the accesibility to access 2. check if set ip is with in subnet range 3. Check if Primary and Secondary DNS is correct as per network settings 4. Set the Default Gateway IP to match the router's IP or the company network's default gateway IP.

3rd part meter not communication

Reason - 1. Memory map configuration wrong 2. (10 power -4 )Conversion factor is not available in third party memory map configuration 3. Data on modscan and software is matching but not matching with meter display readings Solution: 1. Verify data via Modscan, check wiring, confirm the meter parameter's datatype/function code in the memory map, and ensure the gateway supports that parameter datatype. 2. Can be added from conversion factor available in Master settings

Could not download certificate

Reason - All mandatory fields are not saved in organisation info settings Solution: All details should be given in mandatory field of organisation settings

Utilization Categories Contactors

Updated: Sep 01, 2026 | 6 min read

Technical Articles

Published: Jul 14, 2026 by Sandeep Pawar

Technical Articles

No headings found on this page.

Contactors are most commonly used in applications concerning control of electric motors. They are used to start, stop, reverse, jog and plug the motors depending upon the application requirement. Contactors along with thermal overload relays also provide protection to the motor against overloads.

The most basic data required for contactor selection is the motor HP rating and it's rated current. However this data is alone not sufficient. The type of load, duty cycle of the load, switching frequency are some of the factors that influence contactor selection. The switching capability of contactors is majorly dependent on the type of application, and hence international standards (IEC 60947-4-1) specify utilization categories which cover a broad range of applications. These utilization categories and the data associated with them are used by manufacturers to establish contactor ratings.

Kind of Current	Utilization Categories	Additional Category Designation	Typical Load
AC	AC - 1	General use	Non-inductive or slightly inductive loads
	AC - 2		Slip-ring motors or mixed resistive and inductive loads, including moderate overloads
	AC - 3		Squirrel-cage motors: starting, switching off motors during running, reversing
	AC - 3e		Squirrel-cage motors with higher locked rotor current: starting, switching off motors during running, reversing
	AC - 4		Squirrel-cage motors: starting, plugging, inching
	AC - 5a	Ballast Incandescent	Discharge lamps
	AC - 5b	Ballast Incandescent	AC incandescent lamps
	AC - 6a	General use	Transformers
	AC - 6b		Capacitor banks
	AC - 7a		Slightly inductive loads for household appliances and similar applications
	AC - 7b		Motor-loads for household applications
	AC - 8a		Hermetic refrigerant compressor motor control with manual resetting of overload releases
	AC - 8b		Hermetic refrigerant compressor motor control with automatic resetting of overload releases
	AC - 15		Control of AC electromagnetic loads
DC	DC - 1	Incandescent	Non-inductive or slightly inductive loads
	DC - 3		Shunt-motors: starting, plugging, inching, dynamic braking of DC motors
	DC - 5		Series-motors: starting, plugging, inching, dynamic braking of DC motors
	DC - 6		DC incandescent lamps
	DC - 13		Control of DC electromagnetic loads

Kind of Current	Utilization Categories	Additional Category Designation	Typical Load
AC	AC - 1	General use	Non-inductive or slightly inductive loads
	AC - 2		Slip-ring motors or mixed resistive and inductive loads, including moderate overloads
	AC - 3		Squirrel-cage motors: starting, switching off motors during running, reversing
	AC - 3e		Squirrel-cage motors with higher locked rotor current: starting, switching off motors during running, reversing
	AC - 4		Squirrel-cage motors: starting, plugging, inching
	AC - 5a	Ballast Incandescent	Discharge lamps
	AC - 5b	Ballast Incandescent	AC incandescent lamps
	AC - 6a	General use	Transformers
	AC - 6b		Capacitor banks
	AC - 7a		Slightly inductive loads for household appliances and similar applications
	AC - 7b		Motor-loads for household applications
	AC - 8a		Hermetic refrigerant compressor motor control with manual resetting of overload releases
	AC - 8b		Hermetic refrigerant compressor motor control with automatic resetting of overload releases
	AC - 15		Control of AC electromagnetic loads
DC	DC - 1	Incandescent	Non-inductive or slightly inductive loads
	DC - 3		Shunt-motors: starting, plugging, inching, dynamic braking of DC motors
	DC - 5		Series-motors: starting, plugging, inching, dynamic braking of DC motors
	DC - 6		DC incandescent lamps
	DC - 13		Control of DC electromagnetic loads

The utilization categories as per IEC 60947-4-1 are as follow

MO platform provides switching solutions for all utilization categories mentioned above.

AC-1

Contactors with an AC-1 rating are intended for applications involving switching of non-inductive or slightly inductive loads. Heating, lighting, switching of power supply in a power panel etc are some of the examples of AC-1 loads.

AC-2

Contactors with an AC-2 rating are intended for applications involving switching of Slip-ring motors or mixed resistive and inductive loads, including moderate overloads. Some cranes use slip-ring motors.

AC-3

Contactors with an AC-3 rating are intended for switching of Squirrel-cage motors. The contactor must withstand the high starting current of the motor during making. The breaking will be at rated current of motor during running condition. These contactors can also be used in reversing applications. AC-3 category may be used for occasional inching (jogging) or plugging for limited time periods such as machine set-up. During these limited time periods, the number of such operations should not exceed 5 per minute or more than 10 in a ten minute period. Some examples of this application are Compressors, Pumps, Fans, Conveyors, Mixers, Agitators, Air conditioners, Elevators etc

AC-4

Contactors with an AC-4 rating are intended for switching of Squirrel-cage motors. The contactor must withstand the high starting current of the motor during making. The breaking will also be at high starting current of motor as it is used in inching or plugging applications. Some examples of this application are Printing presses, Wire drawing machines, Centrifuges etc

The conditions are as given below,

Table (a):

1) For Ie < 17 A, cos Ø = 0.65, For Ie > 17 A, cos Ø = 0.35

Where

I_e = Rated Operational Current
U_e = Rated Operational Voltage
U_r = Recovery Voltage
I_c = Making and breaking current

Normal Operation
Utilization Categories	Making Conditions			Breaking Conditions
	Ic / Ie	Ur / Ue	cosØ	I / Ie	U / Ue	cosØ
AC - 1	1	1	0.8	1	1	0.95
AC - 2	2.5	1	0.65	2.5	1	0.65
AC - 3 / AC - 3e	6	1	1)	1	0.17	1)
AC - 4	6	1	1)	6	1	1)

Normal Operation
Utilization Categories	Making Conditions			Breaking Conditions
	Ic / Ie	Ur / Ue	cosØ	I / Ie	U / Ue	cosØ
AC - 1	1	1	0.8	1	1	0.95
AC - 2	2.5	1	0.65	2.5	1	0.65
AC - 3 / AC - 3e	6	1	1)	1	0.17	1)
AC - 4	6	1	1)	6	1	1)

Utilization categories most encountered in contactor applications are AC-3 and AC-4

The making and breaking capacities of contactors are dependent on the utilization categories and the standard specifies that the contactors or starters shall be capable of making and breaking currents without failure under the conditions stated.

Table (b):

1) For 17A < Ie < 100 A, cos Ø = 0.45, For Ie > 100 A, cos Ø = 0.35.

Occasional Operation (50 Operating Cycles)
Utilization Categories	Making Conditions			Breaking Conditions
	Ic / Ie	Ur / Ue	cosØ	I / Ie	U / Ue	cosØ
AC - 1	1.5	1.05	0.8	1.5	1.05	0.8
AC - 2	4	1.05	0.65	4	1.05	0.65
AC - 3	10	1.05	1)	8	1.05	1)
AC - 3e	13	1.05	1)	8.5	1.05	1)
AC - 4	12	1.05	1)	10	1.05	1)

Occasional Operation (50 Operating Cycles)
Utilization Categories	Making Conditions			Breaking Conditions
	Ic / Ie	Ur / Ue	cosØ	I / Ie	U / Ue	cosØ
AC - 1	1.5	1.05	0.8	1.5	1.05	0.8
AC - 2	4	1.05	0.65	4	1.05	0.65
AC - 3	10	1.05	1)	8	1.05	1)
AC - 3e	13	1.05	1)	8.5	1.05	1)
AC - 4	12	1.05	1)	10	1.05	1)

Selection Criteria

The starting current of a squirrel cage induction motor is 6 times while that of slip ring induction motor is 2.5 times the rated current. Starting current in slip ring induction motor is less because of the higher rotor resistance in the rotor circuit, which can be effectively removed in steps as the motor attains its rated speed.

From the above Table (a) it can be seen that, for AC-3 / AC3e utilization category during normal operation the contactor must be capable of making 6 times the rated current. The current that contactor must break, however remains the rated current. This is because the AC-3 / AC-3e utilization category specifies that the motor is switched off after it starts running.

In the case of AC-4 utilization category, the current, the contactor must be capable of making as well as breaking remains 6 times the rated current. This is because AC-4 utilization category involves plugging and inching operations, in which the motor is switched on and off frequently.

Hence it can be concluded that AC-4 utilization category is more severe than AC-3 / AC-3e and the switching capability of contactors (Operating cycles/Hr) for AC-4 is lower than that of AC-3 / AC-3e.

Table (b) specifies the values of currents the contactor must be capable of making or breaking under abnormal conditions which occur occasionally. Here also it can be concluded that AC-4 utilization category is the most severe among all the other utilization categories.

Also it can be seen that making and breaking capacities for AC-4 category is more than that of AC-3 / AC-3e, clearly highlighting that AC-4 is severe than AC-3 / AC-3e.

Selection Example

Contactor must be selected such that the making and breaking capacities during both normal as well as abnormal conditions must be within contactor making and breaking capacity.

Motor Operation in AC-3 Utilization category

Normal Operation

Making current of the contactor = 61n = 90A
Breaking current of the contactor = In = 15A

Abnormal operation

Making current of the contactor = 13In = 195A
Breaking current of the contactor = 8.5In = 127.5A

Hence, in both cases, we can select M01 8 which has Rated Current of 18A, Making Capacity of 450A and Breaking Capacity of 350A which is higher than the abnormal making and breaking currents calculated above.

Consider a 10 HP squirrel cage Induction motor with Direct On-Line (DOL) starting.

Rated Current of the motor In = 1 5A

Motor Operation in AC-4 Utilization category

Normal Operation

Making current of the contactor = 61n = 90A
Breaking current of the contactor = 6In = 90A

Abnormal operation

Making current of the contactor = 12In = 180A
Breaking current of the contactor = 10In = 150A

AC-5A

Contactors with an AC-5A rating are intended for applications involving the direct control of electric discharge lamps or other non-motor loads. These contactors are engineered to handle the unique characteristics of inductive loads associated with lighting systems, such as ballasts.

AC-5B

The AC-5B rating for contactors designates their suitability for applications involving the direct control of incandescent lamps.

AC-6A

Contactors with AC-6a rating can be used for switching transformers. Such contactors require high inrush current withstand capability as such currents are expected when switching transformer.

AC-6b

Contactors with AC-6b rating are intended for switching capacitor banks. As there is very high switching surge during switching of capacitors, the contactors are fitted with early make contacts along with current limiting resistors to limit the surge current. Capacitor duty contactors with such resistor blocks have been developed in the MO platform. They are called MOC contactors. Ac-6b rating are available in technical specifications of MOC capacitor duty contactors.

AC-7a

Contactors with AC-7a ratings can be used for slightly inductive loads for household appliances and similar applications. Modular contactors with AC-7a utilization categories are available.

AC-7b

Contactors with AC-7b ratings can be used for Motor-loads for household applications. Modular contactors with AC-7b utilization categories are available.

AC-8A

This category is specifically for contactors designed for use in Hermetic refrigerant compressor motor control with manual resetting overloads. A hermetic refrigerant compressor motor is a combination consisting of a compressor and a motor, both of which are enclosed in the same housing, with no external shaft or shaft seals, the motor operating in the refrigerant.

AC-8B

This category is for contactors used in Hermetic refrigerant compressor motor control with automatic resetting overloads.

These utilization categories help in the selection and application of contactors based on the specific nature of the load and the operational requirements, ensuring that the contactors are appropriately matched to the intended use, thus promoting safety and optimal performance.

Understanding these ratings is crucial for selecting the right contactor for an application, as it ensures that the contactor can handle the specific electrical loads and operational conditions it will encounter.

Rating	AC-1 (A)	AC-2 (A)	AC-3 (A)	AC-3e (A)	AC-4 (A)	AC-5a (A)	AC-5b (A)	AC-6a (A)	AC-8a (A)	AC-8b (A)
MO 9	30	9	9	9	9	9	9	4	12	11.5
MO 12	32	12	12	12	12	12	12	5	16	15.5
MO 18	32	18	18	18	18	18	18	8	22	23.5
MO 25	45	25	25	25	25	25	25	11	30	32.5
MO 32	50	32	32	32	32	32	32	14	40	41.5
MO 40	50	40	40	40	40	40	40	18	50	52
MO 45	50	45	45	45	45	45	45	20	55	58.5
MO 50	100	50	50	50	50	50	50	22	63	65
MO 60	100	60	60	60	60	60	60	26	73	78
MO 70	100	70	70	70	70	70	70	30	85	91
MO 80	125	80	80	80	80	80	80	35	95	104
MO 95	125	95	95	95	95	95	95	42	120	123.5
MO 110	140	110	110	110	110	110	110	50	140	143
MO 140	250	140	140	140	140	140	140	63	165	182
MO 185	275	185	185	185	185	185	185	83	220	240.5
MO 225	275	225	225	225	225	225	225	101	270	292.5
MO 250	400	250	250	250	250	250	250	113	300	325
MO 300	500	300	300	300	300	300	300	135	360	390

Rating	AC-1 (A)	AC-2 (A)	AC-3 (A)	AC-3e (A)	AC-4 (A)	AC-5a (A)	AC-5b (A)	AC-6a (A)	AC-8a (A)	AC-8b (A)
MO 9	30	9	9	9	9	9	9	4	12	11.5
MO 12	32	12	12	12	12	12	12	5	16	15.5
MO 18	32	18	18	18	18	18	18	8	22	23.5
MO 25	45	25	25	25	25	25	25	11	30	32.5
MO 32	50	32	32	32	32	32	32	14	40	41.5
MO 40	50	40	40	40	40	40	40	18	50	52
MO 45	50	45	45	45	45	45	45	20	55	58.5
MO 50	100	50	50	50	50	50	50	22	63	65
MO 60	100	60	60	60	60	60	60	26	73	78
MO 70	100	70	70	70	70	70	70	30	85	91
MO 80	125	80	80	80	80	80	80	35	95	104
MO 95	125	95	95	95	95	95	95	42	120	123.5
MO 110	140	110	110	110	110	110	110	50	140	143
MO 140	250	140	140	140	140	140	140	63	165	182
MO 185	275	185	185	185	185	185	185	83	220	240.5
MO 225	275	225	225	225	225	225	225	101	270	292.5
MO 250	400	250	250	250	250	250	250	113	300	325
MO 300	500	300	300	300	300	300	300	135	360	390

All the above ratings are at operational voltage of 41 5V.

AC-1 5 and DC-1 3 ratings are available in technical specifications of MOO control contactors.

Modular contactors with AC-7a and AC-7b utilization categories are also available.

Previous Next

About the Author

Sandeep Pawar,

General Manager - Product Management

Electrical Engineer with over 20 years of experience in Product Management and Application Engineering for Protection Relays, Power Quality Solutions, and Intelligent Motor Control Centres (MCCs). Possesses strong expertise in LV and MV power system protection schemes, motor protection, monitoring, and control applications. Well-versed in both conventional and intelligent motor management systems, with extensive knowledge of protection, control, and condition monitoring solutions.

Assistance Required?

Select an option to Contact Us

Contact Sales

Contact Support