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2.20.8.1 Wear and Fatigue Monitoring. Where permanently affixed fatigue/wear monitoring systems are used, a self test or automatic diagnostic indication shall be provided as part of the monitoring system. Should the monitoring system become inoperative during automatic operation, the elevator shall not be permitted to resume automatic operation after a normal stop at a landing. When portable fatigue/wear monitoring systems are used, a self test or automatic diagnostic indication shall be provided as part of the monitoring system.

2.20.8.2 Protection Against Traction Loss. All electric traction elevators shall be provided with a traction loss detection means to detect loss of traction between suspension members and drive sheave [See 8.6.1.2.1(f)]. This means shall:

(a) be based upon the type of suspension members and the application;

(b) detect relative motion (See 2.20.11, 8.10.2.2.2(v)(3) and 8.11.2.3.11) between the drive sheave and suspension members and function in accordance with 2.20.8.2(c) in not greater than the smaller of the following:

(1) 45 seconds

(2) the time for traveling the full travel, plus 10s, with a minimum of 20s if the full travel is less than 10s.

NOTE [2.20.8.2(b)]: This relative motion between suspension members and drive sheave is independent of normal creep (See Sect. 1.3) of the suspension members. Compliance with the detection requirement can be accomplished by any method which will determine the relative position of the suspension means with respect to the rotational position of the drive sheave. This can be accomplished by timers, position and velocity measuring devices, as an example.

(c) when actuated, cause the removal of electrical power from the driving machine motor and brake. The means shall comply with the requirements of 2.26.4.4, 2.26.7, 2.26.8.3, 2.26.9.5.3 and 2.26.9.6.3. No single ground shall render the traction loss detection means ineffective.

(d) once actuated by traction loss, comply with the following:

(1) the traction loss detection means shall remain actuated until manually reset,

(2) the car shall not start or run unless the traction loss detection means is manually reset. [See 8.6.1.2.1(f) and 8.6.11.x]

(3) the manual reset means shall be key-operated or behind a locked cover. The key shall be Group 1 Security. (See 8.1),

(4) the removal or restoration of main line power shall not reset the traction loss detection means. (e) be arranged to be tested in accordance with the requirements in 8.10.2.2.2(v)(3)(c) and 8.11.2.3.11. (f) be included in the Maintenance Control Program, [See 8.6.1.2.1(f)] with sufficient detail to ensure that testing can be accomplished by elevator personnel.

General Rationale for 2.20.8.2:

Failure of the suspension members or traction sheave can occur due to the loss of traction between the suspension members and driving sheave. A means to detect traction loss is necessary to remove power from the driving machine motor and brake before either of these failures occur. The requirements have been written in performance language enabling manufacturers to set appropriate parameters for the type of suspension used and the method of detection, but still have quantifiable criteria for verification

purposes. The requirements cover all types of suspension members and traction sheave materials. The proposal recognizes the following:

1. Over the last few decades, the ratio of the car weight to the rated load (C/L) has decreased due to design optimization and the use of lightweight materials, thereby increasing the potential for traction loss as an empty, or lightly-loaded, car approaches the top terminal landing.

2. Measures to detect and protect against loss of traction have been implemented by elevator

manufacturers, although not required by the A17.1 Code. This has contributed to the safety record of steel wire ropes.

Making these measures mandatory merely formalizes the status quo and does not unnecessarily penalize elevators provided with steel wire ropes, but in fact, requires a common denominator for safety.

Certain inspections and tests, such as, traction tests, and maintenance or repair actions may cause the loss of traction. During this testing period, it may be necessary to render ineffective these protection means. The Maintenance Control Program (MCP), 8.6.1.2.1, is required to provide precautions for performing such actions when the protection means is made inoperative or ineffective. The method of verification of the system will depend on the nature of the suspension means system and must be provided in the MCP.

It is essential that, before the elevator is returned to service after actuation of the traction loss detection means, the suspension means are inspected to determine if they are within the replacement criteria of ASME A17.6, 1.10, 2.9, and 3.8 and replaced, if necessary. In addition, the traction sheave shall also be examined and repaired or replaced, if necessary.

Rationale for 2.20.8.2, 2.20.8.2(a) and 2.20.8.2(b): This requirement provides detection of traction loss between the suspension means and the drive sheave within specified parameters. The robustness of the suspension means is specified in the engineering tests in 2.20.11. These parameters are taken from ASME A17.1 Requirement 5.8.1.7.2 and are also based on requirements in the EN81-1 Code Sections 12.10.1 and 12.10.2. These codified requirements in ASME A17 and EN81 have withstood the test of time.

The requirement causes the removal of electrical power from the driving machine motor and brake similar to the Requirements of EN81-1, Clause 12.10.1. This is more stringent than A17.1 requirement 5.8.1.7.2.

Rationale for 2.20.8.2.(c): The new requirements provide for additional assurance that the traction loss detection means will not be made ineffective by EMC, or the failure of power to be removed from the driving machine motor and brake, or to a single ground, or any permanent device not permitted by the code. The traction loss detection means will remove power from the driving machine motor and brake. Rationale for 2.20.8.2(d): Once loss of traction is detected these requirements ensure shutting the elevator system down and remedial action taken before restoration of service by elevator personnel.

Add new requirement 2.20.11

2.20.11 Suspension System Test. Reserved.