Three Phase Electro-Mechanical Watt-hour Meter (DT58)

General
The DT58 three-phase four-wire meter is designed to meet the latest IEC60521 and BS EN 60521 standards for measuring active energy in three-phase four-wire alternating current power grids. Connection is direct or by instrument transformers. The meter is KEMA certified. It has an average service life (MTTF) of 20 years and maximum overload capacity of 600%Ib.

1.Meter case
It meets the protection requirements set by protection class IP53 of IEC60529. The series types of cases and terminal covers are available.
2.Terminals & Terminal block
Terminals:
The connection terminals are made of nickel-plated brass with features of high mechanical strength, good conductivity and corrosion-resistance.
Terminal block:
The terminal block is injection molded of heat- and fire-resistant Bakelite. The voltage test link can be located inside or outside of the meter case.
3.Driving system
The driving system employs three single electromagnet elements, all of which are mounted on the meter frame with three screws. Each electromagnet element consists of voltage element, current element and connection board.
4.Rotor
The rotor shaft is turned of high strength aluminum alloy. The upper end of the shaft is pressed with a worm which is made of thermoplastic, and the lower end is embedded with a graphite bearing which is self-lubricate and friction-resistant to ensure long service life of the meter.
5.Braking element
The magnet is made of AlNiCo5 alloy and designed as U-shaped so that the effect of short time over currents upon the magnet is negligible. A temperature compensation plate, made of a special alloy, is embedded in the braking magnet. The rotor speed can be adjusted largely and continuously by rotating the whole magnet.
6.Frame
The frame is die-casted by high quality SiAl alloy. Its structure is designed as W-shaped of stable property to avoid distortion, and its surface is treated with chromate to achieve reliable and durable coating against oxidation.
7.Upper bearing    
The pin is made of abrasion-proof stainless steel, and pressed into the brass sleeve. It is the rotor guide and runs in the plastic worm of the rotor.
8.Lower bearing    
The magnetic suspension bearing consists of two ring shaped magnets, a guide pin and a bearing base. The pin made of stainless steel runs in the graphite sleeve of the rotor. No lubrication is needed.
9.Register
The cyclometer type register consists of six drums. It can be read directly. The drum is made of polycarbonate. The framework is embedded with a high-strength self-lubricating plastic bearing. No lubrication of bearings is needed during the service life.

10. Technical data
1 Meter type:DT58
2 Standards:IEC60521.IEC514
3 Accuracy(according to IEC60521)
Transformer operated: Class 1
Direct connected: Class 2
4 Average service life (MTTF): 20 years
5(6) Basic current (Maximum current)A: 1.5(6) 3(6) 5(20) 5(40) 10(60) 15(60) 20(80)
7 Rating current of transformer in 5A direct connection
8 Reference voltage Un 3X57.7/100V, 3X220/380V, 3X230/400V, 3X240/415V
9 Reference frequency: 50 Hz.60 Hz
10 Power losses in voltage circuit at 50 Hz Un: 1.0 W/4.5 VA
11 Power losses incurrent circuit at 50Hz Un Ib <0.5 VA
12 Non-running with no-load: 0.8~1.1Un
13 Starting current: 0.4%Ib 0.5%Ib
14 Mean temperature coefficient: From 0.1Ib to Imax at unity PF From 0.2Ib to Imax at unity 0.5 lagging <0.08%/0C<0.12%/0C
15 Insulation level: Withstand A.C. Voltage for 50 Hz, 1min Withstand impulse voltage 1.2/50us>2 kV (when bakelite base>4kV) >6kV (when bakelite base>8kV)
16 Rated load torque at unity PF, Ib>800uNm
17 Weight of rotor48 g
18 Weight of meter=3.5kg
19 Meter base: Steel, Bakelite, and PC
20 Meter cover: Bakelite, transparent PC
21 Terminal cover: ABS, Bakelite, PC
22 Register: Cyclometer single, Unidirectional, Jumping
23 Option Reverse running stopper