Thyristors Snubbers | FMCC Group

Thyristor Snubber Capacitors

Introduction

Thyristor snubber capacitor technology, particularly for rectifier circuits where bi-directional voltages are experienced, have traditionally used film and foil construction in order to accommodate the ac conditions involved.

Application

NCL thyristor snubber capacitors are suitable for a wide range of inverter and converter applications. They are particularly useful for thyristor controlled rectifier circuits such as dc power transmission and traction lineside equipment.

Technology

NCL has developed a range of metallised capacitors, specifically for thyristor snubber applications, which are also fully ac rated. The special dielectric system ensures that the self-healing mechanism cannot produce catastrophic failure. In addition, the design ensures that high peak currents can be repetitively withstood without long term damage.

These capacitors are normally housed in fire resistant epoxy resin; a proven, extremely robust encapsulation, suitable for the rigours of severe vibration and high ambient temperature conditions of traction duty. Alternatively, although not detailed here, the older style metal-cased units may also be accommodated. Please contact us for these designs if required.

Characteristics

The following parameters are applicable to the ranges of capacitors which follow this introductory section. Should there be a particular combination of capacitance value or voltage not given, or should there be a dimensional constraint, please contact us for a design suited to your particular needs.

Capacitance value:	0.22µF to 2.0µF
Tolerance:	± 5%
Voltage rating (Udc):	1750 V to 3500 V
Peak repetitive voltage (UN):	2800 V to 5600 V
Peak non-repetitive voltage (Us):	4100 V to 8100 V
RMS Voltage (Umax):	1250V rms to 2500V rms
Loss angle (tandf):	<0.0003 at 1 kHz
Insulation resistance:	>10,000 sec
Current rating:	Up to 84 A rms, depending on capacitance, voltage rating and thermal constraints
Operating temperature:	-40 to +70°C
Storage temperature:	-40 to +85°C
Connections/tightening torque:	M6 x 6 mm internal thread brass connection - 3 Nm M8 x 8 mm internal thread brass connection - 6 Nm
International standard:	In accordance with IEC 61071& IEC 61881

ZC - 4000V range
Udc = 1750V		UN = 2800V				Us = 4000V			Umax = 1250V rms
C (µF)	Imax (Arms)	Ip (A)	Rs (mW)	L (nH)	Rq (°C/W)	Ø (±2 mm)	H (±2 mm)	Thread	Part Number
0.33	9	150	4.01	8	12.08	40	73	M6 x 6	ZC2600
0.50	14	225	2.65	8	10.43	45	73	M6 x 6	ZC2601
0.68	19	300	1.95	8	8.74	50	77	M8 x 8	ZC2602
0.75	21	335	1.76	8	7.74	55	77	M8 x 8	ZC2603
1.00	28	450	1.32	8	6.91	60	77	M8 x 8	ZC2604
1.25	35	560	1.06	8	6.22	65	77	M8 x 8	ZC2605
1.50	42	675	0.88	8	5.64	70	77	M8 x 8	ZC2606
2.00	56	895	0.66	8	4.71	80	77	M8 x 8	ZC2607

ZC - 6500V range
Udc = 2800V		UN = 4500V				Us = 6500V			Umax = 1600V rms
C (µF)	Imax (Arms)	Ip (A)	Rs (mW)	L (nH)	Rq (°C/W)	Ø (±2 mm)	H (±2 mm)	Thread	Part Number
0.33	6	100	6.83	12	6.48	40	116	M6 x 6	ZC2147
0.50	10	150	4.55	12	5.65	45	116	M6 x 6	ZC2115
0.68	13	200	3.35	12	5.00	50	120	M8 x 8	ZC2116
0.75	14	225	3.03	12	5.00	50	120	M8 x 8	ZC2148
1.00	19	300	2.28	12	4.46	55	120	M8 x 8	ZC2105
1.25	24	380	1.82	12	3.73	60	120	M8 x 8	ZC2178
1.50	28	450	1.52	12	3.64	65	120	M8 x 8	ZC2149
1.75	33	530	1.30	12	3.13	70	120	M8 x 8	ZC2179
2.00	38	600	1.14	12	3.05	75	120	M8 x 8	ZC2150

ZC - 8000V range
Udc = 3500V		UN = 5600V				Us = 8000V			Umax = 2500V rms
C (µF)	Imax (Arms)	Ip (A)	Rs (mW)	L (nH)	Rq (°C/W)	Ø (±2 mm)	H (±2 mm)	Thread	Part Number
0.22	12	200	6.00	15	6.19	45	133	M6 x 6	ZC2550
0.33	19	295	4.01	15	5.33	50	137	M8 x 8	ZC2552
0.50	28	450	2.65	15	4.30	60	137	M8 x 8	ZC2554
0.75	40	675	1.76	15	3.58	70	137	M8 x 8	ZC2556
1.00	50	900	1.32	15	3.04	80	137	M8 x 8	ZC2557
1.25	58	1120	1.06	15	2.82	85	137	M8 x 8	ZC2558
1.50	68	1340	0.88	15	2.45	95	137	M8 x 8	ZC2559
2.00	84	1800	0.66	15	2.16	105	137	M8 x 8	ZC2561

FMCC EUROPE Components and technical solutions for power electronics

FMCC EUROPE
Components and technical solutions for power electronics