Vref

3.3V=

CT Current Transformers

Sensor	Range (Rms Amps)	Burden Resistor (Ω)	Calibration Coefficient (theoretical)	Input rating (mA)
SCT-013-000	100	24	83.33	50
60	39	51.28	30
50	47	42.55	25.0
40	56.2	35.59	20.0
30	75	26.67	15.0
25	91	21.98	12.5
20	120	16.67	10.0
SCT-006 20A/25mA	20	47	17.02	25.0
SCT-019 200A/33mA	200	33	181.82	33.0
SCT-024 400A/100mA	400	12	333.33	100.0
SCT-031 600A/100mA	600	12	500.0	100.0

All voltage reported as RMS value in the table below.

Sensor	Range @ sensor input	Range @ board input	RD1 (Ω)	RD2(Ω)	Gain Resistor RF (Ω)	Gain Resistor RG (Ω)	Calibration Coefficient (theoretical)
Any ac/ac adaptor up to 14.5V output	(EU) 77DE-06-09: 290V (UK) 77DB-06-09: 300V (US) 77DA-10-09: 145V	14.5V	53.6kΩ	4.7kΩ	0	∞	(EU) 77DE-06-09: 248.1 (UK) 77DB-06-09: 256.6 (US) 77DA-10-09: 124.04
ZMPT_1X_225*	329V	0.2V	0Ω	∞	22kΩ	4.7kΩ	281.65
ZMPT_1X_280	291V	0.145V	0Ω	∞	33kΩ	4.7kΩ	249.34
ZMPT_1X_140	145V	0.145V	0Ω	∞	33kΩ	4.7kΩ	124.67