Is anyone running a surface grinder on anything less than an extreme duty 5hp level converter? I've been told by one company that I should use this level converter yet another says that the system will run fine on the base level 3hp.
The system has a 1hp spindle motor, a 1/2hp hydraulic pump motor, and a lube pump motor that is maybe 1/4hp, I can't find any reference to the hp of it but it only pushes lube oil to the ways.
Thoughts?
Thanks
Are you sure all the motors are 3 phase? I have a Sheldon lathe that runs on 3 phase, but only the spindle drive motor is 3 phase. The gear motor that powers the Worthington drive speed control is single phase. In addition the voltage for all the controls is only single phase 120.
My bad.
It's a rotary. My understanding is that a static can't handle more than 1 machine at a time and only allows the motor to develop 2/3 of the rated power.
Thanks Mark.
You are correct as to the number of motors a static phase converter
can start at one time. However I just purchased a North America HL-1.5 static converter for use on a Black Diamond drill grinder. According to the literature it can power multiple machines if the combine load is within the maximum amperage rating of the converter
AND they are started one at a time. One caveat is that the motor(s) shouldn't be started more than a combined total of 6 times an hour. I have not tried using it to start multiple motors, and when using the grinder every time I've started it I run it for well over an hour before shutting it down. So far it's been used to sharpen over 300 drill bits at about 100 bits per session. It runs fine, has plenty of power, and doesn't overheat.
The static converter on the mill is a Phase A Matic PAM 300HD. This model was recommended because of the forward to reverse motor switching when tapping. It has been in use over 15 years and has had no trouble instantly reversing the motor hundreds if not thousands of times over the years. The only downside to this converter is that it's almost 4 times more expensive than the North America HL-1.5.
Keep in mind a static converter uses a series of capacitors to generate a temporary 3rd phase only at the startup of the motor. Once the motor is at speed the capacitors drop out and the motor runs on single phase. Since the 3 phase motor is running on single phase power only 2/3 of the coils are energized, thus the 1/3 loss of power.
Having said that I have 4 machines in the shop running on static converters, a Bridgeport mill, a Racine power hacksaw, a Sheldon lathe, and a Black Diamond drill grinder. All are worked hard and none seem to be lacking power.