A Latching relay: Used for call registration,direction selection or as selector relays
Two types are: Set/Rest are electrical and Mechanical Latching
... [Show More] relays
Need to know latching relay symbol, Its a box with shaded triangle in lower right hand corner.
Which relay do you need to Order
710 Pg, 7
RPM = 60 ∙ ƒ ÷ P÷2 =
Step 1. 60 x Frequency (Hz.) =
Step 2. Poles ÷ 2 =
Take answer 1 and ÷ by answer 2 =
Know the formula for RPM
435 Pg. 5
If you are referring to a megohm meter, it is a test of the insulation properties of such things as electric wiring, motor windings and high power antenna mounts.
We use a "megger" or "meg out" electrical wiring and equipment to see if it is shorted to ground or the frame in any way.
The megger uses much higher voltages to check resistance than a normal Volt-ohm meter.
Minimum resistance is 1 Meg Ohm
Know what a Megger is and what it does
636 Pg. 13
(1) A parallel connection. (2) A resistive element placed across the terminals of an armature to bypass a portion of the current. (3) A flexible electrical conductor designed to conduct current around the mechanical joint between two conductors. (4) The resistive element (Usually of very low resistance) used in parallel with a DC ammeter movement to bypass a calibrated portion of the total circuit current.
Shunt Overloads
425 All Pages
Bad Ground
You are using a Temp Run Box and you get shocked! Why!
520 Pg. 4
The bridle hitch can consist of two,three, or four single hitches (fig. 3-22), used together to form a bridle hitch for hoisting an object
A sling with two legs used to lift a 1,000 pound object will have 500 pounds of the load on each leg when the sling angle is 90 degrees. The load stress on each leg increases as the angle decreases; and if the sling angle was 30 degrees lifting the same 1,000 pound object, the load will be 1,000 pounds on each leg. Try to keep all sling angles greater than 45 degrees; sling angles approaching 30 degrees are considered extremely hazardous and must be avoided at all cost.
Bridal Hitch
128 Pg 17
Scaffolding should be tied to the structure using
#9 wire or tie-in devices. The first vertical tie
should be at the maximum height of 4 times the
narrowest base dimension. Additional ties are not
to exceed 26' vertically. Maximum horizontal
distance between ties is not to exceed 30'.
Scaffolding, You have 32' of rise, you are using 3x5 scaffolding. Where will the tie off points be ?
140 PG. 287-288
Counterweights (Typically) are hung to counter balance the weight of the car PLUS 40% of Capacity Load.
How much should Counterweight way?
240 Pg. 14
Note: We do not use wire smaller than #20 in travelling cables and #24 outside travelers.
Largest wires are feeders to Hoist /Pump motor
We always have 10 % spares
10% of 52 = 5.2
On a calculator Multiply the percent 10 by the number you have and ÷ by 100
10 X 52 ÷ 100 = 5.2
Pulling Spare Wires (Example) 10% of 52 Wires
515 Pg.26
The correct lube must be used on chains.
The freight door motor is spinning but the door wont move, Why?
535 Pg. 9
Lula: Limited use/Limited Access (Example Wheelchair Lifts)
Max Rise 25'
Max Speed 30 Ft/Min
Max Capacity 1400 Lbs.
Max Platform Area 18 Sq/Ft.
Residential Elevator:
Max Rise 50 '
Max Speed 40 Ft/min
Max Capacity 940 Lbs.
Max Platform Area 19 Sq/Ft
840 Pg 2
Dumbwaiters:
Platform limited to 9 Sq/Ft
Inside height is limited to no more than 4 Feet
Capacity is limited to 500Lbs
No Riders
Read Lula and Dumb waiters
545 Pg 1
You never get on top and you work only partially in with the main line OFF
If you get on top of Dumbwaiter what must be done?
545 Pg 14
Notes:(Pi) π is 3.1416 and 231 Cubic inches to the Gallon
Area:
Remember to ÷ 6" ÷ 2 = 3 to get Radius
Area = π∙ r²
Area = 3.1416 x 3 x 3 = 28.27 inches or 3.146 x 9 = 28.27
Volume
Multiple are times height to solve for Volume
V = A∙H
V = 28.27 x 300 (25" feet x 12" = 300)
V = 8481 Cubic Inches
Since we already know there are 231 cubic inches to the gallon
8481 ÷ 231 = 36.71 Gallons
PSI Formula and Gallons (Example) How much oil to move a 6" jack 25'
815 Pg 10
Relief Valve :
Must be tested Annually
Its is simply Pressure relief (If car strikes obstruction,Overloaded Car,Car hits stop ring)
If set to light Car may not move!
Check Valve:
It is simply a one way valve permitting oil to flow in one direction
Up Valve:
The most complicated valve in system
Controls Up Start and acceleration to high speed, up slow down, up leveling speed, and up stopping.
Down Valve:
Because the elevator is not running when on the down direction the down valve depends on system pressure.
Bypass and Relief Valve:
Have been combined into one
Valve Operation
815 Pg 16,17
Simply:
In a Inverting Op Amp (INPUT) is supplied to the Negative
In a Non Inverting Op Amp (INPUT) is supplied to Positive
Amplifiers (Inverting and Non Inverting)
640 Pg 11
Minimum is 2 switches 15 lbs. and must stop the lift within 2"
In a vertical lift how many sensors are required (Pan Switches)
845 Pg Unknown
SCRs are used in DC door motor control and more commonly in Direct Drives (Replacing DC Generators)
SCR is a three terminal device. It basically acts as an on/off switch by pulsing the gate of the SCR with a positive voltage.
Once an SCR is turned on it remains on, till anode and cathode voltages equalize or the anode and cathode are reversed biased or voltage is removed from the anode and cathode.
SCR's
635 Pg12
A Meter with the positive lead on the Anode and the negative lead on the Cathode.
A jumper is placed across the Anode and Gate as well
This should show .7 Volts an indication of a Good SCR
SCR Example:
635 Pg 14 Figure 26
In this figure 11 (Pg 7 Unit 625) it shows R¹ which controls the rate that the magnetic field builds.
R¹ controls the time it takes for the brake to energize after BR contact closes.
R² is in the discharge path of the brake coil. It controls the time it takes for the brake to set after the BR contact opens.
R² also controls voltage spikes from the collapsing magnetic lines of the brake coil when discharging. Thus reducing spikes from reaching other parts of the circuit.
Inductance In A DC Brake Circuit
625 Pg 7 Figure 11
Off Delay Timing Circuit:
A typical door timing circuit is shown Figure 30
By installing the diode across the discharge resistor(RD) The capacitor will charge fast.This ensures full door timing should the closing cycle be interrupted. When the contacts are open the capacitor discharge can not flow thru the diode but must flow thru the (RD) resistor.
The timer described is OFF Delay which means the relay picks as soon as the switch or contact closes.
Timing begins when the current from the feed is removed.
ON Delay Timing Circuit:
Figure 31 When the switch or contacts close the relay is delayed being energized until the capacitors charged.In an On Delay circuit the capacitor is connected in parallel.
Off Delay and On Delay Timer Cicuits
710 Pg 16
When the Generator and Hoist motor armature are connected in parallel they form a closed loop.In this configuration car speed is controlled by controlling the amount of current passing thru the generator shunt field.
To achieve nearly constant speed under changing loads , The Ward Leonard System of automatic armature voltage control has been in use for 1/2 century.
This system also regenerates power back thru the generator to the AC mains, and an energy cost is realized.
Ward Leonard System
425 Pg 7,17
Extension tubes and ties
Rack and Pinion Hoist (Outside Hoist) Contractor wants to move the hoist, what do you need?
850 pg 11,12
Incorrect column line or incorrect benchmark
Escalator is 10 inches too low, what was wrong?
825 Pg 12
Mark along the top portion of incline and bottom. (Not on curved section)Measure in between.
Measure Down!
Advance the escalator till the bottom line is at the top and place new line at bottom using first measurement. Continue to do this till you reach first measurement. Add all together.
Note: Last measurement will be shorter than the rest.
How do you measure an Escalator Hand Rail
835 Pg 14 (Figure 14)
Moving walkway Max angle is 12°
Escalator Max angle is 30°
What is Maximum Incline of Moving Walkway? (Example)
The moving walkway is at 10° in the field, how much more of an angle could it be at?
830 Pg 6
Run High Speed
Ward Leonard System (See unit 425 Pg 18 Figure 17)
Question : If all three contacts close what will happen?
425 Pg 18 Figure 17 [Show Less]