OK guys. Need some help here as this has been a thorn in my side for quite a while. We are an industrial machinery builder that is UL508A certified for building our electrical control panels. Our UL inspector has come in and flagged our Type 12 enclosures and said we need to "de-rate them"...
This section of the NEC tells how to calculate full load amps of multi-motor equipment. I understand how this works, I know when to use the FLA tables for wire sizing etc. My question: When listing the FLA on a piece of equipment and/or wiring diagram, do you use the actual motor nameplate or...
NEC code section 670.3(A) states the following:
“The full-load current shown on the nameplate shall not be less than the sum of the full-load currents required for all motors and other equipment that may be in operation at the same time under normal conditions of use. Where unusual type loads...
I’ve always been confused on this. When calculating the FLA of a piece of equipment or panel for purposes of feeder wire and disconnect sizing etc., the code states to add in 125% of the largest motor FLA. My question is: what if two or more of largest motors are the same size? Our pump...
OK, this is a strange one. We build industrial machinery which we test in our shop via temporary pigtails to a fused bus system. Our QC guy was reaching onto a 480V panel to read voltage across the distribution block. All of a sudden, there was an arc flash. The distribution block he was...
One of our dealers is asking for an up-charge for a machine that will connect to a 660V supply. The only information we have from him is that it’s somewhere in the middle east. This is a two part question:
1. Who uses 660V 3 phase systems?
2. Where can you find control transformers that will...
A little background first:
We have been purchasing a centrifugal pump/motor combination for several years. We’ve frequently had problems in the field with the branch circuit fuses blowing during startup. They are Type J and sized at 175% of nameplate FLA. That being said, the motor is a...
We have a machine in the field with a Yaskawa V1000 15HP VFD installed in it. It is running a conveyor. We are controlling the speed via a 4-20mA signal to the drive which varies from 0-60Hz. We used the canned “Conveyor” setup from the menu.
Here’s the problem. When the customer runs the...
Help me out. I’m a bit confused. We build industrial control panels for industrial machinery per UL508a. We use an instantaneous circuit breaker as the machine/panel disconnect. The current panel I am designing has two 30HP motors, one 0.5HP motor, and a 500VA control transformer. All of...
We are sending a machine to Australia. I have a copy of AS/NZS 3000 “Wiring Rules”. I even have a copy of EN 60204-1, but I know Australia is not currently a CE country. I’m designing the electrical control panel and would like to follow proper color codes and fusing rules, etc. It seems to...
The current issue of “Skeptic” magazine has an article which discusses hot rock geothermal. It’s also known as Hot Dry Rock (HDR) or Hot Fractured Rock (HFR). With all of the discussion about alternate fuels, this is one that I had not been aware of. Apparently, the Australians have been...
I am designing a UL508 panel for industrial machinery. I’m starting two 50HP 230/3/60 motors with FLA of 116A each. I typically use Siemens Type E self protected starters, but due to the larger current rating I’m exceeding the highest amp rating of the series. I’d like to use a solid state...
We produce a model of machinery that comes standard with a MicroLogix 1500 and a 9300-RADKIT modem for dial up troubleshooting and support. The modem talks to Comm. 1 via RS232 DF1. The problem is that this machine is sometimes installed outside or far away from a dedicated phone line. The...
Has anyone experienced this problem? We seem to have a recent problem with the MicroLogix 1500 LRP processors. Randomly, we have had unused bits go high and integer values re-write themselves. In one instance, the first 20 timer presets in the program all reset themselves to 0. We have the...
OK, we have an order for two machines going to Brazil. The voltage there is 380V/3PH/60Hz. We use Weg motors that just happen to be built in Brazil. For some strange reason, they are telling us this is a long lead custom item that will take months to get. IT'S BRAZIL'S STANDARD VOLTAGE AND...
