alt/az cabinet set-up procedure

La Silla DIMM upgrade,

Motor modification report.

NOTE: update doc number here. Update the issue and date in the change record.

Issue: Draft 1

Date: 2 Feb 1999

Prepared by: M. Ravensbergen.

Change record.

Issue:	Date:	Section/Page affected:	Comments:
Draft 1	2 Feb 1999	All	First draft

TABLE OF CONTENTS

1. Introduction *

2. Reference documentation *

3. THETA motor *

3.1. Disassembly and check *

3.2. Re-assembly *

3.2.1. Oil seal *

3.2.2. Gear box backlash *

3.2.3. Encoder mounting *

3.2.4. Limit switches *

3.2.5. Motor mounting *

3.3. Functional test *

4. ETA motor *

4.1. Disassembly and check *

4.2. Re-assembly *

4.2.1. Oil seal *

4.2.2. Gear box backlash *

4.2.3. Encoder mounting *

4.2.4. Limit switches *

4.2.5. Motor mounting *

4.3. Functional test *

5. Installation notes *

5.1. Motors *

5.2. Cables *

5.3. Telescope *

5.4. Telescope control cabinet *

5.5. TCCD *

Introduction

This document describes the modifications that are to be done on the La Silla Seeing Monitor drive motor in order to upgrade them for compliance with the VLT environment.

It also describes remaining issues as per the date of packing (5 Feb 1999)

The modification is done according to "ASM Seeing Monitor, Modifications to the Motor Assembly.",

VLT-PRO-ESO-17413-1275, Draft 3, 3 Mar. 1997.

Reference documentation

RD1 Drawing ‘Seeing monitor, Ensemble Motorisation’. Originator: AMOS. DWG number 1043 02 3/00/00 Rev. D, dated 15 nov 1988.

THETA motor

Disassembly and check

Motor looks in good shape from the outside, after removing the cover RD1 item 1.

Motor gear RD1 item 19 has effectively no fat. There are some remnants of oil. Hopefully, lubrication has been sufficient.

Checked play in 2^nd gear box RD1 item 24 before removing telescope bearing. The intermediate axis can rotate about 60 deg before the friction torque of the bearing is felt. This is definitively too much play. The telescope axis will have a backlash of 60/360 deg which is about 15 arcmin. This axis must have suffered from bad tracking at speed reversals and with getting the center of gravity over the highest point.

Motor has a spring RD1 item 70 that was deformed and bended. It has touched the motor cover RD1 item 6 and also the gear screws RD1 item 50. This MUST have caused ‘jumps’ in the tracking. Spring removed.

Re-assembly

Oil seal

The oil seal RD1 item 31 exchanged and orientation changed.

Gear box backlash

The gear box RD1 item 24 exchanged. Screws and fixed ring sealed with Locktite.

Encoder mounting

New encoder mounted mounted according procedure. Hole in toothed wheel on encoder axis too small, drilled to 3 mm.

Limit switches

Mounted 3 limit switches, not use type Baumer IFR 08.24.15., but successor type IFR 08.26.15/L . This type has also a LED. Checked for correct mounting height and fastened with Locktite

Motor mounting

Motor/tacho mounted according procedure

Functional test

Follow the procedure:

Try to rotate the motor axis by hand. OK.

Connect the motor power leads to a power supply and verify that the motor turns with a current of about 4 Amps. OK, actual current at 15V: about 3 Amps.

Verify positive rotation: a positive voltage on motor connector pin 1 must result in clockwise rotation of the telescope axis (seen from telescope axis side). If not, interchange the motor leads at the motor connections.

Checked, seems to be opposite of this. To be checked with s/w, see below.

Verify positive tacho signal: a positive rotation must result in a pos tacho voltage on tacho connector pin 1. If not, interchange the tacho leads at the tachometer. Same note as 3. Velocity loop is stable, so motor and tacho leads should both be interchanged if the positive direction is wrong.

Check the operation of the limit switches. OK, normal range of motion indicated on motor front. OK

Verify that going off-limit in the positive direction is not critical in timing with the encoder zero pulse (important for proper init of the encoder). Rotate the encoder slightly if these 2 points are too close together. NOT TESTED.

ETA motor

Disassembly and check

Motor looks in good shape from the outside, after removing the cover RD1 item 1.

Motor gear RD1 item 19 has effectively no fat. There are some remnants of oil. Hopefully, lubrication has been sufficient.

Main bearing screws were RUSTED. Cleaned up so that at least there is not any more loosening of rust particles.

Checked play in 2^nd gear box RD1 item 24 before removing telescope bearing. The intermediate axis can rotate about 30 deg before the friction torque of the bearing is felt. This is better than theta motor but still too much play. The telescope axis will have a backlash of 30/360 deg which is about 7 arcmin. This axis must have suffered from bad tracking at speed reversals.

Motor had NO spring RD1 item 70.

Re-assembly

Oil seal

The oil seal RD1 item 31 exchanged and orientation changed.

Gear box backlash

The gear box RD1 item 24 exchanged. Screws and fixed ring sealed with Locktite.

Encoder mounting

New encoder mounted mounted according procedure. Hole in toothed wheel on encoder axis too small, drilled to 3 mm.

Limit switches

Mounted 3 limit switches, not use type Baumer IFR 08.24.15., but successor type IFR 08.26.15/L . This type has also a LED. Checked for correct mounting height and fastened with Locktite

Motor mounting

Motor/tacho mounted according procedure

Functional test

Try to rotate the motor axis by hand. OK

Connect the motor power leads to a power supply and verify that the motor turns with a current of about 4 Amps. OK, at 15 V about 3 amps

Verify positive rotation: a positive voltage on motor connector pin 1 must result in clockwise rotation of the telescope axis (seen from telescope axis side). If not, interchange the motor leads at the motor connections.

Same note as Theta motor

Verify positive tacho signal: a positive rotation must result in a pos tacho voltage on tacho connector pin 1. If not, interchange the tacho leads at the tachometer.

Same note as theta motor

Check the operation of the limit switches. OK, operational range indicated on motor front.

Verify that going off-limit in the positive direction is not critical in timing with the encoder zero pulse (important for proper init of the encoder). Rotate the encoder slightly if these 2 points are too close together. NOT tested.

Installation notes

Motors

Motors have been functionally tested with the engineering panel. Not yet tested with s/w.

The following is still necessary:

Cover support rods.

In one of the motors, 2 rods that support the cover mounting ring are defect.

These rods have got an extension to facilitate the new motor/tacho.

It would be good to machine new rods which have the right length (and a bit better M4 thread than the original rods…).

Oil fill and leakage check.

Check of pos rotation direction. After installation of s/w, issue positive speed command and check that this is the right rotation direction. If not, interchange motor leads and also tacho leads.

Test this before mounting in the telescope. The motors can now ‘turn forever’ in the same direction due to the removal of the (useless) preload spring. The interlock will stop the motion at the switch position, but the eng panel (‘manual’) mode overrides this.

The encoders are mounted, but NOT tested.

Cables

Cables between telescope motors and control cabinet are delivered (including 1 spare set), but only 1 set (motor/tacho/limit switches) has been tested. Encoder cables have not been tested.

Telescope

‘North / south’ sensor still missing. Limit switches are in the spare part box. A drawing of the Paranal version is available.

Telescope control cabinet

Cooler unit sensors not mounted yet. As the cabinet is thermally isolated, the best would be to mount the surface sensor on the inside of the cabinet, i.e NOT in the separated box. The air sensor could then stay in the box and this box could be put below the cabinet in the stand. This would be thermally OK as the cabinet is away from the telescope and also outside.

The main power distr box (at the top of the cabinet) has a thermal switch that power-off the whole cabinet in case of temp > 45 deg C.

The cooling MUST run before the doors can be closed.

General I/O bits are provided with optocouplers and screw terminals for control of the enclosure. The associated schematic as only the north/south sensor on it (2 inputs), so 6 more inputs and 8 outputs are available.

VME CPU has been tested. The I/O boards have NOT been tested. Wiring from I/O to hardware has NOT been tested.

Amplifiers are in ‘default’ potmeter setting. Max current limit has been adjusted.

Velocity scaling has been left untouched, should be roughly OK. The system should be checked with the s/w for the same velocity loop scaling. This must correspond with a motor voltage at max speed of about 15V. Note that there is not much reserve here (for safety reasons). If there is not sufficient motor supply voltage available, the scaling must be made such that the speed increases linear with the commanded speed up till the max speed. Note also that the max input speed of the 1^st gear box is 2000 rpm.

Also, the velocity loop gain could be optimized if necessary.

TCCD

CPU board missing. Will be shipped separately.

Don’t forget to power the fan.

Chassis grounding of 24V supply TBD, see email to R Reiss and M Sarazin.

-o-