EV20
DC power supply, 24V 4A ...
Stepper motor isolated power source providing at least 4A at 24VDC.
When choosing and using a power source, be very careful about safety issues, especially proper grounding and fuses. It is beyond the scope of this wiki to give proper instruction on safety issues related to power supplies. Consult a licensed electrician. A pick and place machine is not a Class 2, doubly-insulated appliance and requires proper grounding.
DO NOT RELY ON YOUR POWER SOURCE FOR ESD AND CHASSIS GROUND UNLESS YOU DESIGN, BUILD AND VERIFY IT YOURSELF IN CONSULTATION WITH A LICENSED ELECTRICIAN. For example, if your design uses a standard DC power jack with three wires, you cannot rely upon any of these to be earth ground. Indeed, the Lenovo power jack has 5 wires (2 red, 2 black, 1 blue). None of those can be relied on for earth ground because both of the following provide 24VDC to the same jack:
- The IBM Lenovo AC/DC power adapter uses a 2-prong ungrounded AC plug
- The Anker Lenovo AC/DC power adapter uses a 3-prong grounded AC plug, but can be plugged by mistake into an ungrounded 3-prong wall outlet installed by a previous homeowner.
You must make sure that your chassis is properly earth grounded! Proper grounding minimizes electrocution risk.
Laptop AC/DC power adapters are cheap and ubiquitous, but see CAUTION, above. Laptop power adapters are typically designed for doubly-insulated appliances. Your pick and place machine is NOT a doubly insulated appliance and therefore requires special attention to grounding.
@Sources
It certainly is possible to use a grounded power supply and wire everything properly so that a single three prong grounded wall outlet powers and grounds the machine safely. For example, if you have a bench power supply, then you are home safe provided your wall outlet is grounded. Here are questions to ask yourself to verify your design:
- What is the worse that can happen if a wire breaks?
- Is my wall outlet really grounded?
- Are there fuses to handle shorts?
- Exposed earth ground can be dangerous. Is there at least a 1Mohm resistor between your frame and earth ground?
- What would happen if a small child poked around and played with the machine?
- Should I worry about anything else?