The LD68 single-phase meter is designed to meet the latest IEC 60521. With accuracy of class 2, it measures active energy in single-phase two-wire alternating current power grids. Connection is direct or by instrument transformers. Both symmetrical and sequential connections are available. The meter has passed the reliability test of EPRI, China. It is a reliable long service life meter. The average service life (MTTF) is 25 years and the maximal overload capacity is 667%Ib. Construction Meter case The meter case meets the protection requirements set by protection class IP52 of IEC60529. Terminal block The terminal block is a part of the base and is molded of Bakelite. The voltage test link can be located inside or outside of the meter case. Driving element The driving element consists of a voltage element and a current element, both of which are fixed on the aluminum alloy frame. It has a load curve compensation device and an inductive load adjustment mechanism. Rotor The worm is an un-detachable part of the rotor shaft so that the mesh between the worm and shaft is improved. Both ends of the shaft are embedded with graphite bearing to ensure the long service life of the meter. Braking element Two magnet cubes are die-casted into the frame by aluminum alloy. It has a temperature compensation plate. Frame The frame is die-casted by high quality SiAl alloy of stable property to avoid distortion. It has a low load adjustment mechanism. Upper bearing The upper bearing consists of a guide pin and a brass sleeve, and is fixed into the meter frame by one screw. Lower bearing The meter uses Al-Ni-Co alloy magnetic bearing unless there is special request from the customer. Register The register consists of 5,6 or 7 drums. It adopts heat- and abrasion-proof plastic gears and bearings. No lubrication of bearings is needed during the service life. The drum is made of polycarbonate, and is paragraphed and printed by UV resistant alumina to ensure non-depigmentation. Technical data 1 Meter type HLD68 (LD68) 2 Applicable Standards IEC60521 ,BS5685 3 Accuracy Class 2(according to IEC60521) 4 Average service life (MTTF) 25 years 5 Basic current(Ib) A 1.5 2.5 5 10 15 20 30 6 Maximum current(Imax) A 6 10 20 30 40 60 60 100 80 100 7 Rating current of transformer in 5A direct connection 8 Reference voltage Un 110 V,120V,220V,230V,240V 9 Reference frequency fn 50 Hz,60 Hz 10 Power losses in voltage circuit at 50 Hz Un 1.0 W/5 VA 11 Power losses incurrent circuit at 50Hz Un Ib <0.6 VA 12 Non-running with no-load 0.8~1.1Un 13 Staring current 0.5%Ib 14 Mean temperature coefficient: From 0.1Ib to Imax at unity PFFrom 0.2Ib to Imax at unity 0.5 lagging <0.08%/oC<0.12%/oC 15 Insulation level: Withstand A.C. voltage for 50 Hz, 1min Withstand impulse voltage 1.2/50us >4kV >8kV 16 Rated load torque at unity PF, Ib Over load capacity 600,667%Ib: 420uNm Over load capacity 400%Ib: 500uNm 17 Weight of rotor 26 g 18 Weight of meter =1.3kg 19 Meter base Bakelite 20 Meter cover Transparent PC 21 Terminal cover Bakelite 22 Register Cyclometer single, unidirectional, jumping 23 Option Reverse running stopper, pulse-sampling device