Schindler 3300 / Schindler 5300 Information on noise and vibration.

Transcription

1 Schindler 3300 / Schindler Content Introduction 1. Ride quality Jerk Car acceleration Vertical car vibration Lateral car vibration Sound in the car 2. Sound basics 3. Vibration basics 4. Structure-borne noise Introduction This document is intended to give an introduction to noise and vibration aspects for the Schindler 3300 and Schindler 5300 elevator systems. It gives a short overview of the basics of noise and vibration and specifies the values that customers can expect for these systems. Noise and vibration aspects for an elevator system cover the following areas: Ride quality: sound and vibration inside the car Air-borne noise, e.g. door noise, noise in the elevator shaft Structure-borne noise in walls: important, as it radiates sound into adjacent rooms The basics of these aspects will be presented in chapters 2 to 4. During operation of an elevator, the following types of noise are present: Cooling fan noise (drive and frequency converter) Drive operation noise Relay switching noise (impulse noise) Door noise Guide shoe sliding noise (only during a short phase after installation) Not every type of noise is equally disturbing. This strongly depends on the nature of the noise, relative background noise and on psychological aspects. Please note that noise is defined as unwanted sound, i.e. sound at the wrong place at the wrong time. Schindler Passenger Elevators

2 1. Ride quality. Ride quality is the term that stands for the following set of aspects: Jerk Car acceleration Vertical car vibration Lateral car vibration Sound inside the car 1.1 Jerk Jerk, unit: m/s 3, is the time-derivative of acceleration. If the elevator moves with high jerk, acceleration changes are very abrupt and can be felt as bumps. 1.2 Car acceleration Car acceleration, unit: m/s 2, determines how long it takes before the car reaches its maximum speed. A high acceleration is generally considered uncomfortable, however, it gives the impression that the car moves very fast. 1.3 Vertical car vibration Vibration is also measured as acceleration, unit: m/s 2. This kind of vibration can be felt by the feet of a person, but is also discerned by the stomach and the internal ear. It is mostly caused by vibrations of the drive and frequency converter. These are transferred to the car by the traction media. 1.4 Lateral car vibration Lateral car vibration is caused by non-straightness of the guide rails, play between car and guide rails and non-smooth guide rail transitions. Generally, it causes low-frequent lateral movements of the car. 1.5 Sound in the car Generally, sound levels in elevators should be low enough not to interfere with speech, but hearing the elevator in motion is desirable from a psychological point of view. 2

3 Noise and vibration performance Adjacent rooms1 30 db(a) incl. impulse noise Shaft2 LpAeq 62 db(a) 65 db(a) impulse noise Structure-borne noise3 Octave [Hz] Lamax [db] Landing Door noise4 60 db(a) Pass-by noise 50 db(a) Impulse noise at top floor 55 db(a) Car Sound pressure level LpAeq 50 ±3 db(a) 57 db(a) impulse noise Vibrations (ride quality) Lateral ISO MPtP < 15 mg ISO A95 < 10 ±3 mg Vertical ISO MPtP ISO A95 < 25 mg < 15 ±5 mg 1 VDI :2004 prescribes a maximum permissible A-weighted sound level in adjacent rooms of 30 db(a). It is the responsibility of the architect / building designer to ensure that the walls and roof of the shaft provide enough air-borne and structure-borne noise attenuation. The main parameter is the area-specific mass of the hoistway wall. Table 2 of VDI :2004 provides rules for the design of the walls depending on the room configuration. These rules are based on standard DIN 4109 supplement 1a. 2 VDI :2004 specifies a maximum sound pressure level in the hoistway of 75 db(a). 3 The levels listed are the levels according to VDI :2004. The Schindler 3300 and Schindler 5300 elevator systems generally fulfill these levels with a large margin, depending on the type of wall. 4 VDI :2004 specifies a maximum A-weighted sound pressure level for door noise of 65 db(a). 3

4 Definitions L paeq L pamax Sound A-weighted equivalent sound pressure level: the steady sound level that, over a specified period of time, would produce the same energy equivalence as the fluctuating sound level actually occurring. (Can be interpreted as a mean level and measured directly with an integrating sound level meter.) Maximum A-weighted sound pressure level All sound pressure level measurements require setting «FAST» of the sound level meter. Vibration / structure-borne noise L amax ISO MPtP ISO A95 Maximum acceleration level [db] lin re: m/s 2 ISO-weighted Maximum Peak-to-Peak vibration value, according to ISO 18738:2003 ISO-weighted A95 vibration value according to ISO 18738: % of all peaks of the ISO-weighted signal are below this value. Applicable standards VDI :2004 ISO :1997 ISO 18738:2003 ISO 8041:1990 and Amd.1:1999 Acoustical design for lifts without machine room Mechanical vibration and shock Evaluation of human exposure to whole-body vibration Part 1: General requirements Lifts (elevators) Measurements of lift ride quality Human response to vibration Measuring instrumentation 4

5 2. Sound basics. Sound is an air pressure variation that is sensed by the ears. An example of sound generating equipment is a loudspeaker. The movement of the loudspeaker membrane causes a varying rarefaction and compression of the air in front of it. compression zones + p(t) [Pa] 0 Figure p(t) rarefaction zones The speed with which the rarefied and compressed zones travel away from the speaker is the sound speed c. At room temperature 20 C, c = 344 m/s. The pressure variation p(t) is added to the local atmospheric pressure. It is only this pressure variation that is heard by the ear. To accommodate the large range of human hearing, the sound pressure level (SPL) is defined: L p : = 20 log where: L p Sound pressure level [db] p Instantaneous sound pressure [Pa] Reference pressure, equals 20_Pa (threshold of hearing) p Normally, the sound pressure level is A-weighted, see figure 2.2. An A-weighted sound pressure level is designated with db(a). A-weighting is widely considered the best weighting to represent human hearing. Low-frequency components are strongly attenuated by this type of frequency weighting. t[s] 5

6 f [Hz] Figure 2.2 A-weighting curve 10 Correction [db] Examples of different A-weighted sound pressure levels are shown in table 2.1. Table 2.1 Phenomenon SPL [db(a)] Jet taking off, 25 meters, threshold of pain 140 Live concert 120 Heavy truck at small distance 100 Noisy office 80 Conversational speech, 1 m 60 Room at home 40 Whisper, leaves rustling 20 Threshold of hearing 0 6

7 3. Vibration basics. a [m/s 2 ] a [mg] Table 3.1 The threshold of vibration perception is about 2 3 mg for vertical vibrations. Within the elevator industry, the recognized unit for vibration is milli-g (mg). One mg equals ca m/s 2. Values in mg and m/s 2 can be easily converted using table 3.1. Subjective vibration perception The way people «feel» vibrations depends strongly on the vibration direction. One has to distinguish between vertical vibration and horizontal vibration, the latter often called lateral vibration. The difference in perception is resembled by the ISO-filter that is described in ISO 8041 Amd.1:1999. The filter weighting curves for horizontal and vertical vibrations are shown in figures 3.1 and 3.2. Figure 3.1 Filter weighting curve for horizontal vibrations according to ISO 8041 Amd. 1: Weighting, db 0,1 0,16 0,25 0,4 0,63 1 1,6 2,5 4 6, Frequency, Hz Figure 4.2 Filter weighting curve for vertical vibrations according to ISO 8041 Amd.1:1999 From the weighting curves it can be seen that humans are most sensitive for horizontal vibrations in the frequency range Hz. For vertical vibrations, this range is 5 12 Hz Weighting, db 0,1 0,16 0,25 0,4 0,63 1 1,6 2,5 4 6, Frequency, Hz 7

8 4. Structure-borne noise. Above 20 Hz, vibration may be called structure-borne noise. Such vibrations may generate audible sound. Generally, structure-borne noise can be considered important for frequencies below 1000 Hz. Standard VDI :2004, «Acoustical design for lifts without machine room», presents a guideline for the amount of structure-borne noise that may be present in a hoistway wall of an elevator. The purpose of this guideline is to minimize perception of elevator noise in adjacent rooms according to international standards. Whereas vibrations have unit m/s 2 or mg, structure-borne noise is measured in db because of its strong relation with airborne noise. L a : = 20 log a a 0 where: L a Vibration level [db] a Instantaneous acceleration [m/s 2 ] a 0 Reference acceleration according to ISO, a 0 = m/s 2 The maximum permissible values are listed in table 4.1. Octave band mid-frequency L a,max [Hz] [db] lin re: 1E-6m/s These levels do not automatically guarantee that the sound pressure level in adjacent rooms will not exceed 30 db(a). The walls need to have a specific mass such that this requirement can be fulfilled. Architects and building contractors have the responsibility to assure that the building interface is designed appropriately. Table 4.1 GB-COMM.noise&vib.EN