Reliability
Heavy-Duty Escalator
Escalators are capable of operating with fully specified performance capability while exposed to the following climatic and environmental conditions:
1. Interior installations: Escalators shall be designed to operate in a temperature range of 5 to 120 šF, dry bulb, and all conditions of relative humidity while exposed to airborne dust and debris.
2. Exterior installations: Escalators shall be designed to operate while exposed to the natural elements of weather, including sunlight, rain, slush, snow and ice; all conditions of relative humidity while exposed to salt, deicing chemicals, airborne dust, and debris, and corrosive elements; and in a dry-bulb temperature range of -10 to 105 šF.
Fire protection
1. No wood or wood products shall be used in escalators.
2. LSHF (low-smoke, halogen free) wiring shall be used where commercially available throughout the escalator installation.
3. PVC may not be used in the escalator installation.
Controls and safety devices
Operating controls
a. Escalators shall have key-operated switches, accessible at both upper and lower landings, located on the exterior deck above the newel base. Alternate locations may be used subject to approval by the owner.
b. Each keyed switch shall be clearly and permanently labeled, including starting and direction selection.
c. Interlocks shall be provided to bring the escalator to a smooth stop, in either direction of travel, before a change of direction may be made.
Safety devices
a. Safety devices include but are not limited to those required by the edition of ASME A17.1 in effect
for this installation.
a. A lockable stop switch or disconnect shall be provided in both pits of escalators.
b. A switch shall prevent operation of the escalator if any part of the floor plate is not in place. This shall not be a manual reset device.
Motors
The driving motors are AC induction motors with starters. Voltage 480 VAC, three phase, frequency 50 / 60 Hz. The motors are totally enclosed with external cooling fins. Protection class shall be equivalent to IP55 insulation group F. Smooth start and smooth stop features are integral to motor, motor switchgear , drive.
Controller
a. The main controller uses a programmable logic controller (PLC) to control and monitor the status of the escalator. The PLC is designed to communicate over Ethernet or approved equal.The PLC has capability to store last 99 or more safety device faults, accessible via laptop connection, panel view or remote communications. Modern PLCs have one dedicated serial port, which supports RS-232-C signals and it provides support for point-to-point and slave SCADA communication protocol systems.
Main control switchgear
The main control switchgear of an escalator contains lockable main switch thermal and magnetic motor protection starter for up and down travel, hour counter, auxiliary contactors, phase failure device, phase sequence monitor and ground fault monitor.
The controller cabinet contains a permanently mounted full-color view panel capable of providing fault and operating data. It is equipped for full-time regenerative variable frequency drive (VFD) capable of full-speed control for maintenance and future âsleep modeâ operation. Generally the escalator is provided with the capability of running at any speed up to specified speed. The speed of the escalator is user selectable and displayed on the HMI.