|
Post by billo2404 on Dec 21, 2014 23:38:12 GMT
Salve, magari è una domanda banale, ma vorrei chiedere se devo abbinare ai miei inverter (OMRON 3G3MV-A2007) la resistenza consigliata sul manuale oppure posso scegliere tra quello che si trova in giro e quali valori è meglio scegliere?
Hi, maybe it's a trivial question, but I would like to ask whether I should combine my inverter (OMRON 3G3MV-A2007) recommended in the manual resistance or I can choose between what is in and what values it is better to choose?
|
|
|
Post by stevant on Dec 23, 2014 11:38:14 GMT
It's important to make sure that if you use an external braking resistor, you get the correct wattage and ohms. I am using 200 watt and 300 ohm resistors. You will also have to activate the resistor in the inverter. At least I had to with the Hitachi WJ-200.
|
|
|
Post by billo2404 on Dec 24, 2014 1:01:53 GMT
Il mio inverter (0,75 kw) vuole una resistenza da 200 ohm, 150 W, ma non riesco a trovare la resistenza con il codice ella omron. è lo stesso se utilizzo una resistenza di altra marca? Se non trovo lo stesso valore posso usare resistenze maggiori o minori di 200 ohm? in questo caso come calcolo la potenza necessaria? My inverter (0,75 Kw) to a 200 ohm, 150 W, but I can't find the resistance with the code she omron. it's the same if I use other brand strength? If you do not find the same value I can use resistors greater than or less than 200 ohm? in this case, how to calculate the power required?
|
|
|
Post by Mitch on Apr 15, 2015 7:55:15 GMT
Il mio inverter (0,75 kw) vuole una resistenza da 200 ohm, 150 W, ma non riesco a trovare la resistenza con il codice ella omron. è lo stesso se utilizzo una resistenza di altra marca? Se non trovo lo stesso valore posso usare resistenze maggiori o minori di 200 ohm? in questo caso come calcolo la potenza necessaria? My inverter (0,75 Kw) to a 200 ohm, 150 W, but I can't find the resistance with the code she omron. it's the same if I use other brand strength? If you do not find the same value I can use resistors greater than or less than 200 ohm? in this case, how to calculate the power required? You may have sorted this out already... If your VFD has a built in braking circuit, and all you need is the resistor, any brand should do provided it has the resistance/wattage required. I believe you can use a resistor with a higher power rating (w) or higher resistance, but not less than 200 Ohm. 200 Ohm 150 Watt on eBay www.ebay.com/itm/Gold-Tone-Aluminium-Clad-Resistor-200W-150-Ohm-Reisistance-/310839077340?pt=LH_DefaultDomain_0&hash=item485f73e9dc
|
|
|
Post by Mitch on Apr 15, 2015 8:03:14 GMT
|
|
|
Post by clyevo on Apr 16, 2015 11:00:05 GMT
what happen if we don use brake resistor. will it damage the inverter? is this true for hitachi wj200?
|
|
|
Post by clyevo on Apr 17, 2015 2:51:42 GMT
So i have done some reading and from what i understand :
-braking resistors will reduce deceleration time for motion simulators -thus, we will be able to reduce deceleration ramp setting in AMC1280 which will result in faster movements and improve reaction of the sim
Usually the inverter has braking transistor which act as a switch to shunt out excess regenerative current from the motor. The braking resistor which we should buy separately will be connected to the braking transistor of the inverter.
How to choose braking resistors: 1) In the data sheet they usually provide recommended watt and ohm of braking resistor 2) too much few resistance will draw too much current going through braking transistor in the inverter thus will damage inverter 3) too few high ohm/resistance will result in slower/inadequate braking 4) the higher the watt the better, the faster the heat dissipated
Please correct me if what i understand is wrong. Thanks.
EDIT : i got he ohm backwards
|
|
|
Post by stevant on Apr 21, 2015 22:53:21 GMT
159 is the minimum so 300 was more than the minimum and figured that would be more than enough as I think it is. It is working for me. You need to turn on the external braking resistor also in the WJ in case you were not aware of that. I guess I could have went to 500 but 300 is still a good amount above the minimum.
|
|
|
Post by Mitch on Apr 22, 2015 1:53:58 GMT
159 is the minimum so 300 was more than the minimum and figured that would be more than enough as I think it is. It is working for me. You need to turn on the external braking resistor also in the WJ in case you were not aware of that. I guess I could have went to 500 but 300 is still a good amount above the minimum. Thanks Stevant. I was looking at the manual for Hitatchi's HBU series braking unit and for the 0.4 kW and 0.75 kW models of WJ200 the HBU uses 200 Ohm so I went ahead and ordered 200 Ohm x 300 Watt ones from eBay - They have shipped already, so I'll let you know how it goes in a few weeks!
|
|
|
Post by stevant on Apr 23, 2015 15:15:37 GMT
I'm sure they will be fine. I assume more would never hurt, it's when you are under is where there would be a problem. I'm sure your 200 will be fine. Good Luck!!
|
|
|
Post by clyevo on May 8, 2015 6:53:22 GMT
I'm sure they will be fine. I assume more would never hurt, it's when you are under is where there would be a problem. I'm sure your 200 will be fine. Good Luck!! From your experience 300 watts is enough for you 1.5 hp motor or does the aluminum heatsink feel really warm?
|
|
|
Post by stevant on Jun 3, 2015 16:18:18 GMT
My motors are 1 hp not 1.5hp. The 300 watt is more than enough, they never even get warm.
|
|
|
Post by clyevo on Jun 4, 2015 15:13:58 GMT
My motors are 1 hp not 1.5hp. The 300 watt is more than enough, they never even get warm. I am using 1.5kw Ac Motor with 60 ratio worm gears Let say platform payload weight 200kg. Let say that a motion like roll put half that weight which is 100kg on the a 20cm (0.2m) arm of a single gearbox shaft (while the other gearbox take the rest of the weight and inertia) Let say that the RPM of the gearbox before decelerating is 28 rpm (3 rad/s) Then kinetic energy = 1/2 x mr2w2 w=3rad/s, m=100kg, r=0.2m Then kinetic energy = 1/2x 100 x 0.2 x 0.2 x 3 x 3 = 180 Joule linkLet say the DC voltage of braking circuit is 240 volts If the resistor is 70 ohm : P=VxV/R 240x240/70 = 822 watts* = 822 joule/sec --------- *here is what your capacity for the braking resistor should be, in this case 822watts If the motor generator efficiency is 80% So it will take 0.8x180/822= 0.1752sec to dissipate 180 joule of energy into the aluminium heatsink If the resistor is 140 ohm, you just double that power and thus the duration If the motor generator is inefficient, less regenerative current will go into braking circuit thus the duration should be lower At 28rpm, Braking torque will be 822/3 = 280 Nm (this is at the final output of gearbox) The vfd itself will also contribute to negative change of torque direction of the gearmotor itself, which is about rated 400Nm but there will increased to 600nm because 150% juice given from vector control during this period. So the combine total torque for braking will be about 600Nm (68% form VFD)+ 280Nm (31% from Braking transistor)=880Nm
Base on this i conclude that 75ohm 700watt braking resistor is apporpriate for me. And of course the 75ohm is recommended by manufacturer, if too low can cause too much current running through braking transistor in the VFD and risk frying it.
|
|
|
Post by clyevo on Nov 1, 2016 6:49:06 GMT
sorry to bring up this old thread, can anyone tell me if i should ground the aluminum brake resistors. Reason is to reduce EMI from the brake resistors. I am sure it is bound to have leaking current to earth from the brake resistors if i do this because i get small jolts when touching the brake resistor during operation. So i am concern it might trip the RCCB if i ground the aluminium brake resistor enclosure.
|
|