Bushing Accessories

Bushing Coupling Units

The bushing coupling units are for permanent installation on power transformers. Together with a matching bushing adapter they serve to make different signals available for measurement and monitoring. The bandwidth of the partial discharge signals extends to 20 MHz. The voltage signal of the built-in capacitive divider serves to synchronize the partial discharge acquisition and to measure the voltage. However, the excellent bandwidth of the voltage signal allows also transfer impedance measurements and tan delta (power factor) measurements.

The bushing coupling unit comes in a IP65 protected enclosure with a PTFE insulated input cable. Thus, it is suitable for indoor and outdoor use. The voltage range and bushing capacitances (C1 and C2) have to be specified on order.

Bushing Adapters

Due to the many different versions of transformer bushings and, hence, bushing test tabs, individual adaptation and flexible installation of bushing accessories are required for testing. Power Diagnostix offers various bushing adapters fitting to many different models of bushing test tabs.

Type	Thread	Size	Connection	Ø	E. g. suitable for
BA2	inside	G¾"	female	4 mm	Micafil: RTKF, RTKG, RTKK, RTF, RTFX 21, RTFX 36
BA3	outside	M45x2	female	8 mm	ABB: GOB 1050-750-110-0.6-B
BA4 adapter	flange inside	-- M76x1.5	male	8 mm	Nanjing Electric: BRLW-500/1250-3
BA5	inside	M24	male	4 mm	HSP: ESKTFK 1050/245-A, OTFS 550/123-0
BA6	outside	M38x1.5	male	4 mm	Micafil: WTF 420/1800 (1978)
BA7C	outside	2 ¼" - 12UNF	female	8 mm	PCORE: POC series 2, CSA standard; ABB: GOE, GSB (245–550 kV)
BA7D	outside	2 ¼" - 12UNF	female	3.5 mm	Trench: OTA 363/1250/1300, OTA (72.5–1200 kV), COTA 1675-H016-23-AG3-01
BA8	inside	5/8" - 11UNC	--	3 mm	ABB: GOB 650/1250/L
BA9	outside	M30x1.5	female	4 mm	HSP: SETFt 600/123-2000, SETFt 1550/420-1800, SETFt 1550/420-2200
BA9B	inside	M30x1.5	female	8 mm	Alstom Grid: P.F. tap
BA10	outside	M16x1.5	female	4 mm	Trench: COT 125-X...1800-X (≥ 123 kV)
BA10B	outside	M16x1.5	female	4 mm	Trench: COT(C) 125-X... 1800-X (< 123 kV)
BA10C	outside	M16x1.5	female	4 mm	Trench: COT 750-800
BA11	flange	--	female	8 mm	ABB: GOA 650, GOA 1050, GOA 1550 400 KV
BA12	outside	M30x2	female	6 mm	NGK: R-D5350D-KEW
BA14	outside	1 1/16" - 12UN	female	8 mm	Transelectrix
BA15	outside	M30x2	female	9 mm	NGK: R-C6200V-LN
BA17	outside	M30x2	female	4 mm	ABB: GOB 250 ... 750/1250, GOB 1050-750-1100-0.6-B, GSA-OA 52/2000, GSA-OA 73/2000, GSA-OA 123-1600, GSA 145/1600, GSA-OA 170/1600
BA18	flange	--	female	8 mm	Mozisolyator: GMTA-90-110/2000
BA19	flange	--	female	8 mm	Mozisolyator: GMTA-45-330/2500
BA21	outside	M24x1.5	female	4 mm	HSP: SETFt 750-170-4000, SESTFt 1050-245-B E6 B, SETFt 1200/245-1250, SETFt 1200/245-3000, SETFt 1425-420-1600, EKTG (72.5-800 kV)
BA21B	outside	M24x1.5	female	4 mm	HSP: OTF (420-800 kV)
BA23	internal	M36x3	female	5 mm	BHEL: Tap Inv. no. BCE-4-1232
BA25	outside	1¼'' - 12UNF	spring	5 mm	PCORE: B-81515-57-70
BA26	outside	1 1/8" - 12UNF	female	¼''	Electro Composites: 350-006-T-730-00
BA27	outside	1 1/8" - 12UNF	female	8 mm	Passoni Villa: PNO, POBO, PAO (<110 kV)
BA28	outside	¾" - 14 NPSM	spring	9 mm	ABB: O Plus (O Plus Dry)

Other adapter models are available on request and will be custom made. For this, Power Diagnostix needs the dimensions of the bushing's test tap (at least a, b, e, and g) as shown with the images below.