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In January 1996, ABB Canada completed delivery and commissioning of the Stobie 7 Cage Hoist revamp. The Stobie 7 Cage Hoist is a double-drum hoist (cage/counterweight) with a hoisting distance of about 4,100 ft. (1,250 metres). The revamped system allows manual, automatic and auto-call operation and serves 21 levels.
The delivery includes: Advant AC-410 based hoist control cubicle; 2 UHM-100 digital hoist monitors; a brake control unit based on the BCC-1 emergency brake control board; control desk with MV-320; hoist data-logger based on IBM PC; base radio control unit mounted in the hoist room; cage control radio unit; portable remote control unit; level boxes based on PowerVent units; DC-drive comprising DCS-500 convertor (3300A, 600V), transformer (13.8 kV/575 V, 2,000 kVA) and UR26 DC-Loop breaker.
There are several unique features of the delivery, some of which are described below:
* Rope stretch compensation software, which allows precise positioning of the cage at levels. The software calculates rope stretch in the shaft caused by actual load condition, as well as the rope stretch accumulated on the drum caused by previously hoisted loads.
There is no magnetic switch on the levels, and the accuracy of the cage positioning is not affected by the rope stretch, which is up to 7 ft. during hoisting or lowering heavy loads.
Automatic Chairing Operation Pressing the chairing button on the level box causes gentle movement up with the speed of about 15 FPM. When the cage position is sufficiently high to engage the chairs (about 1 ft. above the level), the direction is reversed and the cage descends to rest on chairs. The drum movement (rope feed) down direction lasts until the rope tension above the cage is reduced to about 65% of the empty cage load, thus providing secure resting on chairs. The determination of the rope tension above the cage is done in the software from the motor current and position of the conveyances.
* Slack Rope (Cage Stuck) protection in the whole shaft is accomplished using the software. There are no sensing devices in the cage.
* PowerVent-based level boxes are connected and fed from two conductors running down the shaft. The digital and analog signals to and from each box are also transmitted via those two conductors;...