Maintenance (General) Flashcards
Stacker 44 doesn’t have a micro limit switch to show the brake released on the long travel brakes. What does it have instead?
It has a current sensor instead. The current sensor in 44 shows if current is drawn or not, and if that matches the setting of the current put into the device (the device is the current sensor itself; it has a current setting).
This current being drawn doesn’t always mean the brake is drawn in. It just means current is there.
To test if a motor is phase reversed…
Put a clamp on meter around 1 of the 3 conductors and see if current being drawn is more than on a conductor of another motor (can test and reverse phases at breaker of the motor itself).
When hanging up a laminated single line diagram to the wall, what materials do we use?
Silicone on the back of the poster, and duct tape on the edges.
Visually, how is a dc and ac motor distinguishable?
Dc motors do not have the exterior fins (slots on motor housing itself). Ac will (unless small ac motor).
The red handle holding the safety cable for lockout should be closest to the ground or highest lockout point?
Highest for easier access.
Transfer tower 1 has a magnet. Explain how to lock it out.
Lock out the conveyors 1A and 1B. (2A and 2B is not necessary unless going into that danger zone; those conveyors’ tail ends are at the bottom, with their head being at TT2).
Then, climb the TT itself. De energize the control circuit that controls the positioning aspect of the magnet. Also de energize the trolley in the 600V cabinet. Leave the breaker for the magnet itself energized if needed. Then, lock out the cabinet.
(Ensure to not lock out the magnet in the sub unless explicitly directed to do so).
Under what conditions is a bypass suggested over a force on?
If the device is turned off due to malfunction and a bypass is suggested and explicitly approved, a bypass is recommended.
A force is suggested if the device is turned off but healthy and the system needs it to run.
For example, if a magnet is still energized, but there’s a system fault due to the magnet being out of position and the trolley/positioning control circuit is deenergized, force on the input bit for the magnet position to make the output happy, allowing the conveyor, for instance, to run as needed, without the magnet being in position.
On the e300, which two lights should be solid to ensure it works?
MS and NS.
What is an e300? What are its components?
It’s an electronic (smart) overload relay.
The e300 consists of
1) a communication module. This sends info via Ethernet to control architecture (plc bits for instance).
2) a sensing module. This has ability to detect ground faults, voltage of the system, and current flowing in the system.
3) a control module. This contains terminal blocks and Ethernet ports.
What is the megger process?
Firstly, de energize the bucket to be meggered. Then, check with your voltmeter if there is any voltage (as long as bucket isn’t over 600 or 1000v; verify how much meter can handle btw!).
For voltage check, check to ground from each cable.
Then, loosen the wires at the easiest point (breaker or terminal block etc).
Then, connect the black megger lead (negative) to ground. Take the red to each phase one at a time, and test each phase to ground. (Use the right amount of voltage coming from the megger; then hold the test button).
For a healthy motor, want to see high resistance (giga ohms preferably).
Prior to doing the megger test, can check continuity from each phase to ground as well. If the fault is bad enough, you’ll see continuity.
Afterwards, once megger test is done, you can use voltmeter and test each phase to one another via your ohmeter selection.
Why is it important to tighten the screws that lock the cabinet doors?
They’re arc flash rated; they need to be tightened enough to withstand an explosion.
What’s the procedure for pullcord pm’s and inspecting and repairing?
Check to see if turnbuckles are tensioned correctly, and taped. Check to see if station resets well (lubricate it always). Check to see red bulbs work.
If in the field, ensure a gentle enough pull trips the pull cord. Adjust the tension by turning the turnbuckle (one way it’ll turn left to tighten, other way it’ll turn right, so turning one way will tighten in both directions).
If the pull cord station isn’t resetting, hold the pull cord station in reset position and adjust tension (loosen or tighten) until the pull cord station catches and resets.
Tape up the turn buckles to ensure they don’t loosen by themselves.
If in the sub, ensure the trip is shown in the plc, hmi, and that the pull cord relays change positions (have to press b88 if they latch).
How does the temperature gauge work on the transformer?
A metal rod sticks out the back of the faceplate housing that juts into the transformer. The front guage reads according to the bar’s temp.
To test it, loosen the one nut closest to faceplate, pull entire apparatus out, and heat up the bar to the setting where the contacts on the switch (part of temp guage switch) close.
How does the gas pressure gauge on a transformer work? And how do you test it?
The gas pressure gauge contains a diaphragm and an internal relay. The relay responds to oil pressure that rises slowly, causing the gauge to increase. The diaphragm responds to a quick rise in pressure (oil doesn’t empty through pinhole fast enough into compartment, causing diaphragm to fill and push outwards).
To test, turn off the oil valve (part of pipe going into back of the device; it allows oil to cycle through device basically). Then, loosen schroder valve. Take a pump and push air into the piece. This tests the oil pressure alarm. It should trip.
Then, loosen the little cap inside shroder valve, and take it out completely. Then, loosen the spring valve up top. Air should come out, as well as oil at the bottom. This should trip the low oil alarm.
Then, close shroder valve, and the valve for oil. Let it run until oil comes out spring valve. Then close spring valve when guage reading is good.
The shroder valve connects to the diaphragm directly. Loosening it drains oil from diaphragm.
If the shiploader at berth 1 (SL1) goes down, and is in need of a reset (not at the sub 6 feed to it), how is it reset?
At the transformer on ship loader 1. Press ack/reset, and then okay once the error message pops up. (The yellow tripped light will be on).
How are the breakers at SR 44 reset?
If the drive is in the open position, flick up the metal sliding door at the bottom of breaker device. Rack it in, and then, once it is at the farthest it can go, you charge the breaker itself by cranking the plastic handle in the middle of the breaker. Then, the breaker will say charged. Close it at that point.
How does maintenance mode work on the breakers at SR44?
You turn on maintenance mode UPSTREAM of the breakers you are going to turn off (the upstream maintenance mode gives a higher protection level by tripping faster for faults) by switching the switch to maintenance mode enabled.
Do this before switching off breakers. Turn maintenance mode off after reenergization.
How does the ultrasonic sensor we installed on conveyer 2 A/ 2 B work?
It’s an ultrasonic. It measures the distance between itself and the conveyor, detecting large chunks before they hit the TT.
It can act as a switch too. A sensor high will cut off the conveyor in the plc.
At a cell, such as the one in sub 5, the local/remote switch does what?
The local setting allows the contactot to be pulled in locally BUT this setting may not be put in as a part of the plc program. This may cause a fault or alarm (not necessarily severe) in the plc as the control circuit of the cell (consisting of physical limit switches and the like) may send signals such as “closed” to the plc, causing a “fail to open” alarm potentially.
In another scenario, local switch may not be doing anything, depending on if it’s a physical switch or a control circuit switch.
What does the trip/closed switch on a cell, such as in sub 5, control?
The trip opens the contractor (green will show open). Red shows closed. This is used to test the contractor once the umbilical cord is plugged in.
The contractor shouldn’t be racked in at this point. But even if it was, the conveyor wouldn’t start (whether because of the vfd or the coupler not being engaged).
Why does an across the line starter (such as the case with the breaker for conveyor 10B in sub 5) not immediately start the conveyor when racked in?
Because the contactor is to be closed remotely via HMI.
Even if the contactor was closed locally, the conveyor would still not start as the coupler would not be engaged.
On the cells (such as in sub 5), the L1-L2-L3 lights are lit up by which mechanism? And do they indicate the load or line sode?
They indicate the load side. The contactor is racked in, power bleeds through capacitors in the contactor itself, and the current which is leaked into the capacitor is then sent to the LED’s indicating power. They show power in contactor; not the line side.
For a lockout at the cells in Sub 5 for example, how is the cell actually locked out?
Once the contactor is racked out, the red tag line goes through the black cover where the racking out tool is put in, AND through the door itself.
Should the handles of the cells in sub 5 be left in remote or local?
Remote.
What does the breaker control switch on the transformer feed cells (such as in sub 5) control?
It controls the opening and closing of the breaker (not a contactor).
If trouble shooting shiploader 1, and the forward permissive is faulted, what’s a possible troubleshooting solution?
Move it the other way if the reverse permissive is happy, and then see if forward permissive resets itself.
What are four ways of verifying power is dead?
1) the lights on the actual cells
2) verifying knives are out of the shudders and not attached to bus bar
3) opening the bucket and verifying dead power with meter (only on up to 1000v)
4) pressing the local station
To lockout a conveyor, like at sub 5, and there is no E stop on the cell, before racking out, what can you do?
Trip the breaker by flipping the breaker control switch handle.
If there is no E stop, and no way to open the contactor before locking out, what is another way to safely rack out without arcing?
Haven’t the conveyor verified as deselected by checking the hmi performs the same function.
Arcing only occurs in the presence of a load.
