4References

British Standards Institution (2019), BS 4142:2014+A1:2019. Methods for rating and assessing industrial and commercial sound.

British Standards Institution (2014). BS 5228-1:2009+A1:2014. Code of practice for noise and vibration control on construction and open sites - Part 1: Noise.

British Standards Institution (1991), BS 7445-2:1991 Description and measurement of environmental noise – Part 2: Guide to the acquisition of data pertinent to land use.

British Standards Institution (2017), BS EN 61672-2:2013+A1:2017 – Electroacoustics. Sound level meters – Pattern evaluation tests

British Standards Institution (2018), BS EN IEC 60942 – Electroacoustics. Sound Calibrators.

Gange. M (2011), ‘Low-frequency and Tonal Characteristics of Transformer Noise’, Proceedings of ACOUSTICS 2011, Gold Coast, Australia.

International Organisation for Standards (ISO) (2024) ‘ISO 9613-2:2024 – Acoustics – Attenuation of sound during propagation outdoors – Part 2: Engineering method for the prediction of sound pressure levels outdoors’

National Grid (2021), Operational Noise Assessment for the Proposed Little Hosted 400 kV Substation, Available at: https://planning.wealden.gov.uk/Planning/Display/WD/2021/0733/MAJ . Accessed February 2025

Thistle Wind Partners Limited (TWP) (2024) Ayre Offshore Wind Farm Onshore Scoping Report.

 

AOperational Noise Model Source Spectra

A.1: Operational Noise Model Input Spectra (1/1-octave bands)

Plant Item	Sound Power Level (dB) at Octave Band Centre Frequency (Hz)								dB(A)
	63	125	250	500	1,000	2,000	4,000	8,000
400 kV Shunt Reactor incl. Coolers	66	80	87	86	89	84	73	60	93
220 kV Shunt Reactor incl. Coolers	62	76	83	82	85	80	69	56	89
66 kV Shunt Reactor	58	72	79	78	81	76	65	52	85
66 kV Shunt Reactor Cooling Plant	60	67	71	74	74	72	84	78	86
66/0.4 kV Auxiliary Transformer	75	76	70	65	62	55	53	71	80
400 kV Harmonic Filter	63	78	90	81	67	48	48	43	91
220 kV Harmonic Filter	58	73	85	76	62	43	43	38	86
Control Building Heating, Ventilation and Air Conditioning Units	52	63	61	77	73	72	71	56	80

 

 

 

 

 

 

A.2: Transformer Input Spectra (1/3-octave bands)

	Transformer Sound Power Level (dB) at 1/3-Octave Centre Frequency (Hz)																								dB(A)
Type	50	63	80	100	125	160	200	250	315	400	500	630	800	1,000	1,250	1,600	2,000	2,500	3,150	4,000	5,000	6,300	8,000	10,000
400 kV	47	55	58	82	65	63	86	74	87	90	87	84	78	79	79	73	71	69	66	63	64	64	62	60	95
220 kV	40	48	51	75	58	55	79	67	87	83	80	77	71	72	71	66	64	62	59	56	56	57	55	53	90
66 kV	35	43	46	70	53	50	74	62	82	78	75	72	66	67	66	61	59	57	54	51	51	52	50	48	85