How do you size a contactor for a motor?
How do you size a contactor for a motor?
As per above chart:
- Type of Contactor = AC7b.
- Size of Main Contactor = 100%X Full Load Current (Line).
- Size of Main Contactor = 100%x6 = 6 Amp.
- Making/Breaking Capacity of Contactor = Value above Chart x Full Load Current (Line).
- Making/Breaking Capacity of Contactor = 8×6 = 52 Amp.
How is contactor rating calculated?
Making/Breaking Capacity of Contactor=1.5×13= 19 Amp. Size of Star Contactor (Starting Condition) = 33%X Full Load Current (Line). Size of Star Contactor =33%x13 = 4 Amp. Size of Main Contactor (Starting-Transition-Running) = 58%X Full Load Current (Line).
How do I choose a contactor?
When selecting a contactor, please make sure that the contactor’s rated current is specified for the AC-3 load type. Ensure that you are looking at the right table. You can see the rated current for the AC-3 load is lower than the rated current for the AC-1 load.
Can you oversize a contactor?
A contactor is a glorified switch and the ratings are for its own function. You want to avoid under-sizing a contactor, but you can oversize.
How many amps is a size 3 starter good for?
Polyphase Motors
| Maximum Horsepower (hp) | ||
|---|---|---|
| NEMA Size | NEMA Continuous Amp Rating (amps) | Full Voltage Starting |
| 2 | 45 | 15 |
| 3 | 90 | 30 |
| 4 | 135 | 50 |
How many amps does a contactor coil draw?
The Coil does not draw . 5 amps or 55 watts.
How do you calculate contactor coil current?
First, the type of the AC contactor for the motor generally adopts the ac-3 series. Then, the working current of the motor is estimated: I=5.5*2=11A. At last, the working current of the AC contactor can be about: 11*1.5=16.5A….How to Calculate AC Contactor Current Rating for Motor?
| Rated Power | Current ratings | AC Contactor Model |
|---|---|---|
| 15 kW | 30A | CJX2-4010 |
What is AC2 contactor?
AC-2: These are used in slip-ring motors starters such as Switching on and switching off the motor. AC-3: These types of contactors are generally preferred for the starting of Squirrel-cage motors, and switches off motor during the running time which means the contactor can withstand high current continuously. Example.
What are the amperage ratings for a contactor?
Devices switching more than 15 amperes or in circuits rated more than a few kilowatts are usually called contactors.
Are contactors rated per pole?
Contactors are rated by designed load current per contact (pole),maximum fault withstand current, duty cycle, voltage, and coil voltage.
What does res mean on a contactor?
You will notice that the RES (resistive load) rating is higher than the FLA (full load amperage) rating and much lower than the LRA (locked rotor amperage) rating. So, the contactor above would be sufficient to control/switch a 40 amp full load INDUCTIVE load and a 50 amp RESISTIVE load.
How do you size a contactor for a motor? 1 Type of Contactor = AC7b. 2 Size of Main Contactor = 100%X Full Load Current (Line). 3 Size of Main Contactor = 100%x6 = 6 Amp. 4 Making/Breaking Capacity of Contactor = Value above Chart x Full Load Current (Line). 5 Making/Breaking Capacity of Contactor = 8×6 = 52 Amp. More
How are contactors and motor starters rated?
Contactor and Starter Ratings Contactors and motor starters are rated according to size andtype of load they are designed to handle.
What voltage should be used to power a contactor?
You should next confirm the control voltage to be used to power the contactor. This can be the same as the line voltage, however often a lower voltage is selected for the contactor for safety purposes. Generally, coil voltages are 250V or below.
How do you calculate the size of a MainActor?
Type of Contactor = AC7b. Size of Main Contactor = 100%X Full Load Current (Line). Size of Main Contactor = 100%x6 = 6 Amp. Making/Breaking Capacity of Contactor = Value above Chart x Full Load Current (Line).
