BC Electrician
Industrial electrical installations
Industrial installations.  There is so much information to cover here.. This shows what a typical large manufacturing plant would need for power, so we'll start with the incoming High Voltage and follow the flow from there..
Left is one of the Transformers. Depending on the plant size, this could be very large, and  there are often more than one per site.The incoming voltage is 25,000 volts and this mill operates at 460 volts. On the right is the high voltage 25 KV Switch to disconnect it from the source. Center shows the transformer cooling fans.
3333 kva Tranny. 75 amps primary @ 25 KV.Secondary amps 4010 @ 480 Volts
Cooling fans blow air throught the Transformers oil filled heat fins.
25 Kv Switch. Note the brass Key-lock prevents opening door with power on.
Tap Changers on the high voltage side. Must only be operated without power.
These are typical of the guages found on oil filled transformers. They are for temperature, internal pressure, and the oil level. They are often wired to an alarm.
The first stopping point is this 480 volt 2000 amp breaker located in a distribution center.
The 480 volt power from the transformer enters this distribution center.  The breaker shown above is located at the far end, and tied to the rear buss bars where it feeds the fused switches shown in front. Each of these fused switches will feed things such as MCC's or large single motor starters.
Switches that will feed other distribution centers and motor banks.
Feeder cables from switches travel in tray. Here is a ladder type tray feeding a MCC. Note the non- conductive wood cable spacers to keep the cable "free Air" rating.
MCC (Motor Control Center) They house starters, switches, panels, transformers etc. Note the colored numbering system for easy Id.
In this example, the feeders from the switch in the distribution center end up here. This main switch mounted in a MCC will feed the entire MCC buss bars. This is done where it may be either necessary to shut off the entire MCC. This may happen when a group of motors or an entire machine is fed from the MCC. It is convenient because workers are able to "Lock Out" an entire machine at a single location, with one lock.
Switches and Starters are the main reason for MCC's. All in a single location, it allows a large number of devices to be controlled  and fed from a common buss bar.  They are neat and tidy and can save the user a lot of time and money instead of using all single enclosures. The tray to Mcc's can also hold all the cables for many motors and  control for them
Inside the MCC's
Tubs, or Buckets as they are often called. These entire units are removable from the MCC and have contacts that clip to the MCC buss bars, making them plug in units. To the Left we have a size 3 starter. The motor leads connect to the terminals on the end of the wires from the bottom of the contactor. The control wires go to the bottom left side of the tub. Size 3 starters are quite big, so an auxillary relay (Pilot) is used to interface it to a PLC.
This is simply a Fused disconnect Switch. It may feed a transformer, or a VFD, or a capacitor, or heaters, or anything else that needs 480 Volt or 3 phase power.
Above we see a control transformer. they are used to supply power the contactors and also power for hardwired motor control circuits. This includes things like the lights on pushbuttons, and sometimes smaller D.C power supplies. The one shown above also has ground fault lights mounted in the door to indicate if any of the ungrounded delta 480 volt phases has a ground on it.
To the left is a soft start installed in the MCC. This is used to limit the starting current so a large motor can be started without causing a big voltage dip in the lines. They often also have braking abilities to slow a motor down faster as well. These are also often used where too much starting torque could damage or spill something.
Capacitor banks. This one is a  lot more sophicistated than just capacitors. What it does is sits on the 480 volt line and VERY accuatly measures the lag in the power factor. There are not many instances where we have a leading power factor, so they are used for lagging conditions.  This one has been engineered to take Harmonics into consideration and has line capacitors and reactors installed.  The gray colored contactors automatically react to changing conditions and add or remove the capacitors as the power factor changes. With all the features, they can be set to correct to unity (0) powerfactor and often even produce a leading power factor. (Leading is not often a desired level either).  
Capacitors: On a compressor cct with 4 motors. Every time demand requires another motor to start, one of the gray mags in the middle pulls in and one of these caps will start.
Transformer which is fed from an MCC switch
More tray installations. Note how neatly it contains all the cables. Below are some control cables in tray.
Left are 3 local motor disconnects. The 3 wires you see entering each disconnect are a) the lead to the motor, b) the feed from the contactor in the MCC, and c) the blue control cable which goes directly to a PLC. (Usually multi-conductor #16 guage teck). There will be 3 inputs to the PLC. 1 for the start, 1 for the stop, and 1 for the disconnect aux, which turns off the contactor when the handle is pulled so the blades open with no load
A Bank of VFD's (Variable Frequency Drives. They all have features used for speed control, soft starting, and braking.
Note the line and load reactors used to kill harmful harmonics
Banks of cabinets, often used to house things like VFD's, PLC's, Terminal strips, large motor starters etc.
Automation And PLC's
These are pictures of what a typical PLC looks  like in the field. Both are Allan Bradley. Left is a Control Logix with some flex i/o near the bottom, and right is a PLC5 with a remote rack. this will be discussed more in an automation page.
Please note that this is a huge topic, that we'll discuss in greater detal on a future page of their own.
Another Control logix PLC (left) and a typical terminal strip (Right). The Black terminals actually are just fuses (Usually 2amp) inside used to protect the plc output cards that feed things like contactors and solenoids and pilot lights.There is usualy a common 5 amp breaker used to protect the inputs such as photocells, pushbuttons, and limit switches. There are of course many other i/o functions which we'll discuss in greater depth on a future page.  
Miscellaneous Stuff!
Typical Hydraulic unit. Motors and Pumps
Example of a Brake Motor
RTD cables entering a PLC
Motorized Steam Valve with position feedback to a plc
Deisel powered Standby Emergency Generator
Limit Switches to indicate top and bottom limits of travel
I had to include this Picture of a typical application for Festoon Cable.  I always wondered about that name.....
<<< Refrigeration pump shows how a motor is connected with teck cable. Also shows a digital Temperature display
This Page was Co-produced by Bryan Irons...
Thanks Bryan!