8i20 Brake resistor questions
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						27 Apr 2019 16:57				#132106
		by 0ddbod
	
	
		
			
	
			
			 		
													
	
				8i20 Brake resistor questions was created by 0ddbod			
			
				Hello,
The machine that I'm refitting has 2 x 8i20 drives, it's a small lathe with average speed rapids so I don't expect that the brake resistor will see a lot of use.
From the 8i20 manual the brake output can provide 15A.
Does anyone know if the brake output on the drive limits the brake current to 15A?
At 360V maximum braking would be with a 24 ohm resistor, If I use a lower resistance will this simply reduce the level of braking available or will it allow the brake current to exceed 15A possibly damaging the drive?
I'm ok if it just means I have less braking available than the maximum possible, but I don't want to damage the drives.
The brake resistor that I have from the original drive is 16 Ohm which at 360V would allow 22.5A if unlimited.
Second related question, both drives are supplied from the same DC supply, is it ok to connect the brake resistor to only one of the drives or is it possible to connect to brake outputs of both drives together to share the same resistor?
Any comments or thoughts much appreciated.
					The machine that I'm refitting has 2 x 8i20 drives, it's a small lathe with average speed rapids so I don't expect that the brake resistor will see a lot of use.
From the 8i20 manual the brake output can provide 15A.
Does anyone know if the brake output on the drive limits the brake current to 15A?
At 360V maximum braking would be with a 24 ohm resistor, If I use a lower resistance will this simply reduce the level of braking available or will it allow the brake current to exceed 15A possibly damaging the drive?
I'm ok if it just means I have less braking available than the maximum possible, but I don't want to damage the drives.
The brake resistor that I have from the original drive is 16 Ohm which at 360V would allow 22.5A if unlimited.
Second related question, both drives are supplied from the same DC supply, is it ok to connect the brake resistor to only one of the drives or is it possible to connect to brake outputs of both drives together to share the same resistor?
Any comments or thoughts much appreciated.
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						27 Apr 2019 20:10				#132120
		by PCW
	
	
		
			
	
			
			 		
													
	
				Replied by PCW on topic 8i20 Brake resistor questions			
			
				The brake is just a switch, it has no current limiting so the current is limited
entirely by the brake resistor.
Its probably better to just use one brake output since the on/off voltages
will not be exactly the same.
					entirely by the brake resistor.
Its probably better to just use one brake output since the on/off voltages
will not be exactly the same.
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						27 Apr 2019 20:38				#132122
		by 0ddbod
	
	
		
			
	
			
			 		
													
	
				Replied by 0ddbod on topic 8i20 Brake resistor questions			
			
				Thanks for the reply, much appreciated.
I'll get another resistor and go with just using one brake output.
Cheers..
					I'll get another resistor and go with just using one brake output.
Cheers..
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