Acoustics; Test For Prominent Discrete Tones (Pdts); Electromagnetic Immunity - Seagate ST4000VX000 Product Manual

2.10 Acoustics

Drive acoustics are measured as overall A-weighted acoustic sound power levels (no pure tones). All measurements are
consistent with ISO document 7779. Sound power measurements are taken under essentially free-field conditions over a
reflecting plane. For all tests, the drive is oriented with the cover facing upward.
For seek mode tests, the drive is placed in seek mode only.
The number of seeks per second is defined by the following equation:
Note
(Number of seeks per second = 0.4 / (average latency + average access time
Table 3 Fluid Dynamic Bearing (FDB) motor acoustics
Idle Seek
2.3 bels (typical 2.4 bels (typical
2.5 bels (max) 2.5 bels (max)

2.10.1 Test for Prominent Discrete Tones (PDTs)

Seagate follows the ECMA-74 standards for measurement and identification of PDTs. An exception to this process is the
use of the absolute threshold of hearing. Seagate uses this threshold curve (originated in ISO 389-7) to discern tone
audibility and to compensate for the inaudible components of sound prior to computation of tone ratios according to
Annex D of the ECMA-74 standards.

2.11 Electromagnetic immunity

When properly installed in a representative host system, the drive operates without errors or degradation in performance
when subjected to the radio frequency (RF) environments defined in
Table 4 Radio frequency environments
Test
Electrostatic discharge
Radiated RF immunity
Electrical fast transient
Surge immunity
Conducted RF immunity
Voltage dips, interrupts
Seagate NAS HDD and NAS +SRS HDD Product Manual, Rev. E
Description
Contact, HCP, VCP: ± 4 kV; Air: ± 8 kV
80MHz to 1,000MHz, 3 V/m,
80% AM with 1kHz sine
900MHz, 3 V/m, 50% pulse modulation @ 200Hz
± 1 kV on AC mains, ± 0.5 kV on external I/O
± 1 kV differential, ± 2 kV common,
AC mains
150kHz to 80MHz, 3 Vrms, 80% AM with 1kHz sine
0% open, 5 seconds
0% short, 5 seconds
40%, 0.10 seconds
70%, 0.01 seconds
.
Table 4
Performance level
B
A
B
B
A
C
C
C
B
Drive Specifications
Reference standard
EN61000-4-2: 95
EN61000-4-3: 96
ENV50204: 95
EN61000-4-4: 95
EN61000-4-5: 95
EN61000-4-6: 97
EN61000-4-11: 94
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