Automation Direct sells braking resistors.
https://www.automationdirect.com/adc/shopping/catalog/drives_-a-_soft_starters/ac_variable_frequency_drives_(vfd)/vfd_accessories/braking_units_-a-_resistors
Looks like the cheapest one is about $30.
But unless you are hitting the brakes constantly, they usually don't get
hot.
A 300 watt (continuously rated) would be good for a 2+ kw drive if you
aren't using it constantly.
The problem with using a stove element is that you will need to protect
the terminals. A 240 input drive has about a 350v DC bus voltage.
You don't want to get shocked with 350 VDC!
Dave
On 12/24/2020 11:06 AM, Jon Elson wrote:
On 12/24/2020 02:18 AM, Chris Albertson wrote:
"All the time?" When you have a hard requirement like this is when
some
detailed engineering can pay off. Assume you are reversing at 50%
duty
cycle and burning 1KW 50% of the time. Where I live this can cost 12
cents per hour. This is $89 per month if you actually do run "all the
time". Or $1,000 per year. Or maybe you are usig a lower value
resister
and burning 4KW with your brake? That is $4K per year
The VFD only turns the braking resistor on when the DC link voltage
rises above some limit due to energy returned from the motor during
deceleration. I never detect any warming on mine except during rigid
tapping cycles.
A better way is to use a battery inside the power supply. a 100
amp-hour
lithium battery would cost possibly $400.
You are going to need a 340 V battery bank, and a charger for it.
Jon
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