I have an Otis 7stop 200fpm 2500 lb. passenger elevator with a strange problem. The unit uses a 63GA generator UCL controller with capacitor damping. When the elevator goes into decelleration (either direction), the car begins lunging (comming almost to a stop then jerking forward a few inches at a time. The problem seems to be worse in the Down direction, possibly due to the counterweights. This system uses 3 fields- GLF (levelling field) that is fed from the control rectifiers and 2 self excited fields- GSF (series field) and GSEF (self excited field). When the car is lunging, the GLF voltage is fluctuating from 5 to 15 volts, depending on what stage of decelleration it is in. The elevator is doing fine in high speed and there are no noticable voltage fluctuations until FE relay drops. It seems to smooth out slightly, but not completely, when UX or DX relays drop to initiate the final step of decelleration. Using a megger, we have checked all fields and armatures to ground and across each other and find no grounds or shorts. While the GLF voltage is fluctuating, the rectifier output is remaining constant. This problem just showed up one day- there has been no recent generator work done. All generator brushes are good and there is no arcing at the brushes. All capacitors and resistors in the damping circuits check good. I am sure that the lunging is due to the crazy GLF fluctuations. Has anyone out there ever seen anything like this? It is about to whip us.

-- Roger Shumate Local 80 IUEC (rogershumate), September 18, 1997

Answers

my problem was a loose generator brush ring moved 1/2 inch on me check all generator bolts to see if the field connections are tight along with the motor connections and controller connections where generator termanals are..be sure noone has moved any resistor taps .her is the sequence of the glf circut the function of the glf field when the glf fiel is from left to right the car goes up and vise versa through the ga1 brushes...glf establishes rate of retardation gsef plays a major role in this too but your glf current must be firmly established for each step [ FE-HM,,HM-TL,,TL-U-D] speed change process.. after 1e drops out glf is the only shuntstill connected therfore provides a primary control if car does not reach floor and LAT times out to increase glf for a recovery and thus hard stop...FE drops and FE1-2inserts the gf tap1 to 2 resistance in the gsef circut fe 13+14 insert lfr tap4 to 5 resistance in the glf circut generator voltage and speed decrease when fe 11-12 in the 2e coil circut opensumx and dmx 21-22 keep trailing brushes from interfering when 2e drops out gf resistance tap 2- 3 is inserted into the gsef cicut and ga output builds down and fe 3-4 opened.. the lv coil circut wa deenrgized maximun dampening will cause sluggish operation [sequence of glf retardation]

-- jag (thiscarup@aol.com), September 18, 1997.

Tried all of the above-still bouncing

Thanks for responding. We've been through everything you mentioned in both messages.We have checked the series field compounding (problem occurs before SF picks) This unit does not have all of the relays you mentioned (no LAT, DMX, SUMX,) We have been in contact with engineers at Lippert and Nutmeg in Connecticut, who supposedly have nationwide contract withOtis for Generator work. Everyone os confused about why GLF voltage is fluctuating wildly but rectifier voltage remains constant. (This job was put in in 1962)

-- Roger Shumate (rogershumate@msn.com), September 19, 1997.

HEY I THOUGHT OF SOMTHIN TO LOOK AT ALSO.. SORRY BEEN A LONG DAY.. i was examining a set of prints and you say this occours when fe falls out fe falls when stp picks up to stop the car if you look in area 11 of you prints you will see up twards the top you ll see stp contacts 13-14 and 15-16 these are in parallell they strenghthen the motor field and dont fall out till car stops check this relay first......also periodic tightening of the gen loop cicut and cunductance checking will eliminate control and frustrating leveling problems HOPE I HELPED YOU

-- JAG (THISCARUP@AOL.COM), September 18, 1997.

OTIS

Check for opens under your GLF resistor bands which may not be apparent until under current. Also, very rare, check behind the controller for carbon tracking where relay contact terminals are mounted.If there is a loose connection on a high current contact terminal to HL1 or etc. An arc will occur to its nearest terminal {any} and over time a track will occur and will eventually act as a semiconductor.It will look like a carbon lightning bolt behind one of your high amperage relays... Good Luck......

-- Joe McLoone (JMclo30547), September 24, 1997.

RE:LUNGING

THE GLF FIELD SHOULD ONLY COME INTO PLAY WHEN UX OR DX DROPS IT SOUND LIKE A DEFINITE SERIES FIELD PROBLEM. WHAT TYPE OF HOIST MOTOR? AND HAVE YOU TRIED RUNNING WITH BALANCED LOAD? I'VE HAD THIS PROBLEM ON A 2 TO 1 OTIS TRACTION MACHINE #155 WITH AN 83GA GENERATOR 500 FPM. WHAT IS THE LOOP CURRENT WHEN THIS OCCURS AND WHAT IS THE POLARITY! EVEN THOUGH SF IS OUT YOU STILL ARE USING A CONSIDERABLE AMOUNT OF SERIES FIELD WHICH IS ADJUSTABLE.

-- (ROB625@AOL.COM), September 25, 1997.

Could Be!!

We pulled the generator out to have the fields voltage-drop tested and found that 2 poles were shorted together. The generator shop is still rewinding. We will have the generator back Sept. 29- we'll see if that fixed to. Thanks to all that tried to help.

-- Roger (rogershumate@msn.com), September 26, 1997.

Could Be!!

We pulled the generator out to have the fields voltage-drop tested and found that 2 series field poles were shorted together. The generator shop is still rewinding. We will have the generator back Sept. 29- we'll see if that fixed to. Thanks to all that tried to help.

-- Roger (rogershumate@msn.com), September 26, 1997.

Otis

ROB625 is right about UX & DX being back, the resistor bands that should be checked are GF1 for deceleration not the LFR bands.

-- Joe McLoone (JMclo30547), September 26, 1997.

EUREKA!!!

After we had the generator series field rewound, compounded the generator, and allowed a good film to start forming on the commutator, the elevator smoothed out and is now running as good as it ever has. Thanks to all for your advice.

Roger

-- roger (rogershumate@msn.com), October 07, 1997.