Space Heater Wattage Required

[goodoboy]

hello,

What is the typical size wattage for a motor (500hp) space heater used to keep windings dry? How can I calculate this?

Thanks

 

[electric_cal]

There are two commonly used equations to determine the correct watts for a space heater. The two equations usually give different results.
The two formulas are:

1. H = DL/35
where
H = heat, in kilowatts
D = machine end bell diameter, in feet
L = machine length between end bell centers, in feet

2. W = 2DL
where
W = heat, in watts
D = outside diameter of stator laminations, in inches
L = length of stator core, in inches

Formulas were from an EASA publication in 2001.
Hope this helps you.

 

[goodoboy]

There are two commonly used equations to determine the correct watts for a space heater. The two equations usually give different results.
The two formulas are:

1. H = DL/35
where
H = heat, in kilowatts
D = machine end bell diameter, in feet
L = machine length between end bell centers, in feet

2. W = 2DL
where
W = heat, in watts
D = outside diameter of stator laminations, in inches
L = length of stator core, in inches

Formulas were from an EASA publication in 2001.
Hope this helps you.

Thank you. Where can find L and D from?

 

[goodoboy]

can I use the motor frame size to determine the space heater size?

 

[electric_cal]

You could go to the motor manufacturers website and locate the specs on the motor based upon the dataplate information. They could possibly also supply you with thier recommended space heater watts for the motor.

 

[goodoboy]

You could go to the motor manufacturers website and locate the specs on the motor based upon the dataplate information. They could possibly also supply you with thier recommended space heater watts for the motor.

I will look at the nameplate on the motor and hopefully the space heater data is located there.

 

[Dennis Alwon]

All motors are different but 1 Hp= 746 watts--

 

[Dennis Alwon]

I would look in Table 430.250 for 3 phase motors at 500 hp-- assuming 480V it is 590 amps. You can use Watt=Volts*amps

 

[goodoboy]

I would look in Table 430.250 for 3 phase motors at 500 hp-- assuming 480V it is 590 amps. You can use Watt=Volts*amps

Thanks for help. I'm sorry, but how can Table 430.250 help me with determining the space heater wattage?

 

[kwired]

Thanks for help. I'm sorry, but how can Table 430.250 help me with determining the space heater wattage?

I think you need to clarify your OP question, I'm guessing you are trying to determine how much heat is needed from an anti-condensation heater installed within a motor, correct?

I'm guessing there is no one solution fits all method to do this and any attempt to do so is basically just considering worst case condensing conditions.

 

[goodoboy]

I think you need to clarify your OP question, I'm guessing you are trying to determine how much heat is needed from an anti-condensation heater installed within a motor, correct?

I'm guessing there is no one solution fits all method to do this and any attempt to do so is basically just considering worst case condensing conditions.

The problem is. I have a 500W heater, that is measuring .6amps. Heater is connected to 120V supply.

calculations tell me I should be pulling 4.16amps. I think the heater is bad. Just don't know if correct assumption.,

 

[electric_cal]

I would agree that if you are reading .6 amps on the space heater circuit, that you have at least 1 faulty heater. 500 watts for a 500 HP motor would not provide adequate space heating. If you can provide the motor nameplate information here, I will try to get you the space heater data for the motor.

 

[kwired]

The problem is. I have a 500W heater, that is measuring .6amps. Heater is connected to 120V supply.

calculations tell me I should be pulling 4.16amps. I think the heater is bad. Just don't know if correct assumption.,

You still did not clarify the application, and has caused some confusion in some of the replies. In the Op you mentioned a 500HP motor, now you are talking about a 500W heater, kind of only adds to the confusion.

I kind of figured you are trying to determine the size of heater needed to help prevent condensation within a 500 HP motor, now I really don't know what the application is, or exactly what is being asked, please clarify for me as well as others.

 

[goodoboy]

I would agree that if you are reading .6 amps on the space heater circuit, that you have at least 1 faulty heater. 500 watts for a 500 HP motor would not provide adequate space heating. If you can provide the motor nameplate information here, I will try to get you the space heater data for the motor.

Thank you for help.

I was thinking the same as well. This is why I wanted to confirm if I have the right size heater to begin with.

Motor:
HP: 450
Voltage: 2300
Phase : 3
Load speed 1180
size:588

How do you know 500W will not provide adequate heating for 450HP?

 

[goodoboy]

You still did not clarify the application, and has caused some confusion in some of the replies. In the Op you mentioned a 500HP motor, now you are talking about a 500W heater, kind of only adds to the confusion.

I kind of figured you are trying to determine the size of heater needed to help prevent condensation within a 500 HP motor, now I really don't know what the application is, or exactly what is being asked, please clarify for me as well as others.

I apologize, I had incorrect motor data from first post. Sorry. Below is what I have:


Motor:
HP: 450
Voltage: 2300
Phase : 3
Load speed 1180
size:588

Heater:
120V single phase (external source)
435W

The problem is measured amps is .6amps, when calculations show I should be pulling about 4.16amps.

I assume the heater is faulty.

My question is how do I determine what size heater will provide efficient heat to protect against the motor placed in a high condensation location? Or maybe the heater I have is correct size, just needs to be replaced.

Thank you kindly.

 

[electric_cal]

goodoboy, if this will help, we have two 500 HP verticle hollow shaft motors in our shop at this time for service. They are equipped with 120 volt / 400 watt space heaters. They have two 400 watt heater strips inside the windings. There are 4 wires in the space heater junction box, 2 for each space heater, which are connected in parallel when the motor is in place. Can you tell me how many wires are there for the space heater on your motor?

 

[kwired]

I apologize, I had incorrect motor data from first post. Sorry. Below is what I have:


Motor:
HP: 450
Voltage: 2300
Phase : 3
Load speed 1180
size:588

Heater:
120V single phase (external source)
435W

The problem is measured amps is .6amps, when calculations show I should be pulling about 4.16amps.

I assume the heater is faulty.

My question is how do I determine what size heater will provide efficient heat to protect against the motor placed in a high condensation location? Or maybe the heater I have is correct size, just needs to be replaced.

Thank you kindly.

Is is a fixed resistance type of heater? I can't say I am familiar with what is commonly used for these heaters, but if it were like self regulating type of heat cable or something along those lines it would have a higher resistance at a higher temperature. This would kind of make good design sense as the unit would draw less current when not needed, and you certainly wouldn't want something contributing more heat when the motor is running at full load.

 

[goodoboy]

goodoboy, if this will help, we have two 500 HP verticle hollow shaft motors in our shop at this time for service. They are equipped with 120 volt / 400 watt space heaters. They have two 400 watt heater strips inside the windings. There are 4 wires in the space heater junction box, 2 for each space heater, which are connected in parallel when the motor is in place. Can you tell me how many wires are there for the space heater on your motor?

Thank you. I have 2 wires.

 

[goodoboy]

Is is a fixed resistance type of heater? I can't say I am familiar with what is commonly used for these heaters, but if it were like self regulating type of heat cable or something along those lines it would have a higher resistance at a higher temperature. This would kind of make good design sense as the unit would draw less current when not needed, and you certainly wouldn't want something contributing more heat when the motor is running at full load.

I am not sure if its fixed resistance. The motor is not running when the heater is running. Heater turns on when motor is off.

 

[goodoboy]

I wonder if it makes a difference if I measure the current at the power panel instead of load?