Cage hoist No.3 has been upgraded at Belaruskali mine No.3 recently with the electric drive and control system based on Siemens components. The Institute of Mining Electrical Engineering and Automation, SIMATEK and Siemens Belarus were responsible for issuing the electrical part of the project, manufacturing the control system, installing and adjusting the new electrical equipment.

Victor Klemba, head of mining automation department, IGEA, speaks on hoist upgrade details and effects:

- Before the upgrade the hoist had been equipped with a slip-ring asynchronous electric drive with speed control by rotor resistance adjustment. Consequently, approximately half the energy was spent to warm those resistances up only.

So, the old drive was replaced with a modern asynchronous cage motor featuring a frequency converter. As result, no power is needed for warmup, first. Second, power is generated and returned to the mains on nearly a half of the cage travel. The hoist is designed so that a loaded cage shall be driven the first half of the travel by force, while the other half can be travelled on its own, pulled by the weight of the runout rope. Then the motor can generate power instead of consuming it.

- So, there is evident power saving?

- Indeed.

- Is it a brand new concept or similar to any already existing system?

- At the Mining Division No.3 we have implemented the first-ever in the CIS highly efficient variable AC hoist drive which meets all requirements of the national power saving programme. There is a microcontroller based control system which provides the hoist operator with full real-time data on the hoist systems status and performance.

- We know that updated equipment was installed at the Krasnoslobodsky mine hoist. What is different in your product? Are there any other advantages besides reduced power consumption?

- The hoist at the Krasnoslobodsky mine is similar to that at the mine No.3, TSR-6. However, there is a low speed direct DC drive, which is more sophisticated and requires more accessory electrical equipment, including a power mains harmonic filtering system. Besides, it is not as efficient yet as an AC drive. We retained the gearbox in order to avoid unnecessary expenses, therefore, a semi-automatic control variable frequency AC drive could be used at the third mine hoist. That brings a benefit of up-down cycle time reduction by nearly one-third, as the hoist is semi-automatically controlled.

The system is designed so that the automatic means never interfere while operator’s performance is reasonable, but correct his actions in case of a fault or delay. And that reduces the total time, for automatic actions are usually faster and more efficient than human. That’s first. Second, a skilled operator was required for the old machine, the one able to feel the hoist intuitively.

And a not minor advantage is that the upgrade improved personnel safety. Previously, a hoist was not able to stop at the extremities, i.e. at the banking level or bottom level, on its own.

- Whom did you cooperate with while upgrading the hoist?

- We were not the only party involved, of course. SIMATEK company assisted in control system and drive design and adjustment, while Siemens Belarus provided required components, including the electric motor and frequency converter.

We were responsible for the major part of design work, although subcontracted by Belgorkhimprom. Installation and erection works were performed by Trest Shahtospecstroy. Our engineers together with Simatek Group, LLC supervised the installation, and connected the controls, and adjusted the whole system.

Managing staff of the Mining Division No.3 and chief power engineer’s office were closely involved in the upgrade.

It would hardly be feasible with no assistance from the hoisting personnel. The machine was out of service from the late May to the early September, and there was a huge amount of installation, erection, and adjustment work to do during that period.

Just consider replacement of the electric motor, which is as heavy as 14 tons. A special room was cut off the motor room and furnished on purpose for the frequency converter. The control room needed upgrade, too. The motor was replaced along with its supporting frame. Cable routes wanted renovation.

- But what do those who operate the joist think about the upgrade?

Gennady Vorobey, mine No.3 hoist foreman:

- Every upgrade nowadays is focused on a major issue of energy saving. To this end, such hoist upgrade brings visible effect from the very first moment of use. Our power consumption has actually dropped. And we are still running the new equipment in, precisely adjusting hoist components in cooperation with the IGEA.

Kaliyshchik Soligorska, 15/10/2010

By Svetlana REUT, photo by V. PILIPTSOV