Hope everyone that lands on this thread enjoys going over these old schematics as much as I have. I'm a hardware engineer by trade, but will take any job that involves figuring out how to make something work, specially if that something uses technology that is 100 years old.

There are two schematics available for reference:
1) TYPE 6006A CONTROLLER - SCHEMATIC 1
2) TYPE 6006A CONTROLLER - SCHEMATIC 2

The elevator in question services 2 floors and it is controlled with a TYPE 6006A CONTROLLER
- The elevator controller uses relay logic to latch hall and car button calls.
- When the elevator is on the first floor, the controller ignores calls to the 1st floor. This happens because the down limit switch is open.
- When the elevator is on the second floor, the controller ignores calls to the 2nd floor. This happens because the up limit switch is open.
- Once the elevator is moving to a floor, it ignores calls to the opposite floor (e.g. while the elevator is heading to the 2nd floor the elevator will ignore any call to the 1st floor).
- The controller stops the motor when the up/down limit switch opens, which indicate the elevator car has reached the desired floor.
- The door on each floor has an OTIS "L" door contact and an OTIS "L" door lock.

1) OTIS "L" Door Contact


When the door is closed the door contact circuit is closed.

2) OTIS "L" Door Lock


When the elevator car IS NOT in the corresponding floor:
- The door lock prevents a closed door from being opened (and the person opening it falling onto the elevator shaft).
- The door lock contact circuit is closed.

When the elevator car IS in the corresponding floor:
- The door lock is disengaged, allowing to open the door in the corresponding floor.
- The door lock contact circuit is open.

The elevator safety circuits are wired in series to implement a logical AND function. If any of the following circuits is open the motor is stopped (if running) and all elevator calls are ignored:
- 1st floor door is open (OTIS "L" door contact). One of the door interlock contacts shown in the schematic. The door lock should prevent the door from being opened when the elevator IS NOT in the corresponding floor; however, the door can be opened shortly after the elevator starts moving and the door lock is still disengaged by the elevator car rail.
- 2nd floor door is open (OTIS "L" door contact). One of the door interlock contacts shown in the schematic. The door lock should prevent the door from being opened when the elevator IS NOT in the corresponding floor; however, the door can be opened shortly after the elevator starts moving and the door lock is still disengaged by the elevator car rail.
- elevator gate is open.
- emergency stop switch on elevator car is in the down position.
- final limit switch above up limit switch is open.
- final limit switch below down limit switch is open.

Two outstanding questions:
- The elevator car has a limit switch on car that is currently not being used.
- The door lock contact circuit is currently not being used.

1. The limit switch on car is normally open. The circuit only closes when the elevator car is close to the 1st floor landing or the 2nd floor landing.
2. The second schematic shows the limit switch on car (when used) should be used along with the door seq. contacts (when used).
3. The door lock contact is open when the elevator car is close to or at each floor landing.
4. The door lock contact is close when the elevator is in between floor landings.
5. The door contact is open when the door on each floor is open.
6. The door contact is closed when the door on each floor is closed.

Given the previous six statements, I thought the simplest way to implement a door interlock safety function was to use the OTIS "L" door contacts on each door connected in series.
- If either door is open the controller ignores all calls.
- If either door is open while the elevator is moving the motor is stopped, and all future calls are ignored until all doors are closed.

The two outstanding questions are:
Q1) Is there a safer way to implement the door interlock safety function? Can the door interlock contact and/or the limit switch on the car be used in any way to achieve this?
Q2) What is an example of the door seq. contacts (when used) shown in the schematic?

One outstanding issue:
- Motor struggles to bring the elevator car down (counterweights going up).

MOTOR GEARBOX

The motor has a plate with specifications:
- HP 1
- R.P.M. 1200
- VOLTS 220 (Vrms)
- P.H. 1 (phase)
- CYC 60 (Hz)
- AMPS 7 (Arms)

The start and run capacitors are part of the controller, as shown on the schematic.
- The controller uses relay logic to open the motor brake, apply the full line-to-line voltage to the motor (close the accelerator switch), and when to disengage the start capacitor.
- The brake and accelerator coils are driven by the main motor winding voltage (A, B and C main switches) before the accelerator switch (K switches). The accelerator switch has a piston that introduces a time delay that allows enough time for the motor brake to disengage before the full line-to-line voltage is applied to the motor.
- The start capacitor is switched in (H switch) when the main line switch (C auxiliary switch) is engaged.
- After the accelerator switches engage (K switches) and the motor starts rotating, the voltage on the auxiliary motor winding starts to increase. When the motor auxiliary winding voltage increases beyond the voltage set by the power resistor 1HR and the coil 1H make voltage, the start capacitor is latched off (1H switch applies power to 2H coil, which latches power to 2H coil through normally open 2H switch, and removes power from H coil through normally closed 2H switch, which in turn switches out the start capacitor H switch).

The controller has a metal box under it to hold the start and run capacitors.
- The capacitor box had 5 x 27 uF film capacitors.
- Two capacitors were connected in parallel to make the start capacitor (condenser C3 on schematic).
- Three capacitors were connected in parallel to make the run capacitor (condenser C2 on schematic).
- The total start capacitance is 135 uF.
- The total run capacitance is 81 uF.

The old capacitors were replaced with 30 uF 440 VAC film capacitors (SFS44T30J291B-00DU).
- The total start capacitance increased to 150 uF.
- The total run capacitance increased to 90 uF.

Dissipation Factor
- The old capacitors have a measured dissipation factor around 0.5%.
- The new capacitors have a measured dissipation factor around 0.05% (10 times better).

With 5 start capacitors (150uF) and 3 run capacitors (90 uF):
- The motor always starts on the way up and make it to the 2nd floor landing.
- The motor sometimes starts on the way down, but would stall most of the times. When the motor managed to start, it would struggle a lot, particularly close to the 1st floor landing.

With 5 start capacitors (150 uF) and 4 run capacitors (120 uF):
- The motor always starts on the way up and make it to the 2nd floor landing.
- The motor always starts on the way down and make it to the 1st floor landing; however, the motor still struggles a lot, particularly close to the 1st floor landing.

The following links show measurements for voltage, current, power and rotational speed taken while the elevator is going up (white traces) and going down (red traces):
VOLTAGE MEASUREMENT
CURRENT MEASUREMENT
POWER MEASUREMENT
MOTOR SHAFT ROTATING SPEED

The rotational speed shows that the motor IS NOT rotating at the specified rotational speed of 1200 R.P.M.
- Induction motor slip can account for a 2% to 3% reduction in rotation speed.
- The motor shaft rotational speed measurements show the shaft rotates at around 900 R.P.M. when the elevator is going up.
- The motor shaft rotational speed measurements show the shaft rotating in the range of 620-800 R.P.M. when the elevator is going down. The point that the rotational speed reaches 620 R.P.M. is the point at which the motor struggles the most. It sounds like the motor is about to stall. The only reason it doesn't (probably) is because of the increased run capacitance.

Highlights on the outstanding issue:
- The motor was rebuilt. The electric motor shop that rebuilt the motor indicated that they replicated the original number of turns and physical separation of the stator windings.
- The motor stator was rebuilt with 6 poles. The rotation speed of a 6 pole motor should be 1200 R.P.M.; however, the measured rotating speed is lower than the theoretical rotating speed.
- The motor has a harder time when the elevator is going down (counterweights going up). It is expected that the power is higher when the counterweights go up.
- With 90 uF run capacitance the motor stalls on the way down.
- With 120 uF run capacitance the motor draws 18-21 A rms, which is way more than the specified current of 7 Arms.
- With 120 uF the auxiliary winding voltage is 320 V rms and the auxiliary winding current is 19-21 Arms.

Notes on manual operation:
- With the motor brake disengaged is fairly easy, albeit tedious, to move the elevator up and down manually by rotating the motor shaft.
- The up/down force difference required to move the elevator manually is noticeable. It is harder to bring the elevator down (counterweights up), as expected.
- The one thing to note of manual operation is that the motor shaft is nowhere near rotating at 1200 R.P.M.

Questions on the outstanding issue:
Q3) Rather than asking a specific question, I'll take any advice or comment that could help better understand what's causing the motor to struggle so much.


Thank YOU so much for taking the time to read through all this!