How to purchase an excellent electrical measurement device?

Good morning! Today I’d like to talk about some tips of how to purchase electrical measurement devices, and I hope this is useful for you. Electrical measurement device is a concept of general word. As we know, Multi-meter, installation type instruments belong to electrical measurement devices. Here, we mainly discuss how to choose installation type digital meters.
Well, digital meters, according to the function, can divide as follows: Voltage meter, Current meter, Active (Reactive) power meter, Frequency meter, Power Factor meter etc, including the all-in-one function type called intelligent multi-meter. This part mainly discusses some common sense.

Instrument accuracy
Electrical measurement devices include 7 classics: 0.1; 0.2; 0.5; 1.0; 1.5; 2.5; 5.0
The level refers to error percentage of instrument when it come full range.
For example, the accuracy of 193I-9X4 three-phase current meter manufactured by Blue Jay is 0.5 with input current of 5A. That is to say, when this current meter measures full range current of 5A, the maximum of error percentage won’t be 0.5
Another way to discuss device accuracy is called uncertainty level. We’ll talk it next time.

Digital meter and analog meter
Digital meter is known for its precise reading and high accuracy.
The strengths of the analog meter, according to the motion of pointer, we can know the change trend and scope.
Our company, specializing in "power control, power protection automation" equipments, is a fist-class manufacturer. We offer intelligent digital meters for energy saving and eco-friendly.

Power supply
Generally talking, power supply can divide three types, transformer power supply, switch power supply, and the battery.
Transformer power supply:
Strong anti-interference ability and anti-harmonic, but solo input voltage classic that DC not available
Switch power supply:
Wide input voltage range 70~250v Poor anti-interference ability, especially in heavy harmonic places like steel plant

Input measurement signals
The accuracy of DC is far higher than AC.
The true effective and average value
The multi-meter shows average digital of power parameters in a very short period of time.
Installation type meters precisely display power parameters digital in real time, having the characteristics of strong anti-interference ability anti-harmonic and frequency variation.

Optional functions
There are some optional functions, besides the general measurements.
Communication function: Supporting RS485 and MODU BUS protocol
Analog output function: 4~20mA
Control function: When the voltage is overload to setting value, the meter can alarm by relay output.

C/T ratio setting
The full range of current meter can be set based on installation transformer. And the setting value is any one of 5A~8000A according to our country standard.

Respond speed
Digital meters generally adopt specialized chip giving consideration to multi-functions and respond time is slow down. Only 3 ~ 5 digitals are available in one second.
Our company, Blue Jay Electronic digital meters can show 50 digitals in one second with high precision and strong stability. The respond seed is quite fast for customer satisfaction.

Other frequency meters
What we talked above is all about meters of frequency 50 Hz.
But there are some other frequency meters for special field application. Like digital meters of frequency 40 Hz are for aeronautical application, and meters of frequency 20 Hz for super audio power and transformer output current.
Blue Jay Electronic can satisfy customers’ need by manufacturing different frequency of digital meters.

Digital monitor software
When using digital meters with RS485 communication, customer generally has to write digital-monitor programmed manual. That is troublesome.
Our company is for free writing this manual for customers to improve production efficiency. For customers, we do best.
At last, thank you for reading.

Read there to find power meters formats

Blue Jay supply following types of electrical metering device:

Panel Mount Electricity Meters:

These types of Electricity Meters fit into a hole cut into a panel or enclosure. Their size is normally expressed as either a DIN96 or DIN72 being the cut out hole size 96mmx96mm or 72mmx72mm square respectively. Electrically they are available in single phase, three phase, basic kWh only or as Multi-function instruments (these options are further explained below). In addition some models have plug in modules that can be fitted after the meter is installed which offer pulse outputs, MODBUS Communications, Profubus Communications, Analogues Outputs and Alarms etc. To view our range of Panel Mount Energy Meters click this link

DIN Rail Mount Electricity Meters:

These types of Electricity Meters fit inside a panel or enclosure on Top Hat or DIN Rail. Electrically they are available in single phase, three phase, basic kWh only or as Multi-function instruments. DIN Rail Electricity Meters are usually supplied with any pulse or communications options when the meter is bought and cannot generally be added to at a later date.

Tariff / Billing Meters:

Blue Jay 194 series Multifunction Power Meter can add this function, 194Y and 194Q series meter provide 12 segment 4 tariff logger billing, can be used by landlords, caravan park or marina owners to bill their clients and tenants for energy used.

Electricity Meter Options

Pulse Output

A pulse output is a relay contact (more often that not an electronic relay) inside the meter that closes momentarily when the meter advances it energy register. By connecting this up to either a BMS (building Management System) or an Energy management system the remote equipment can count the pulses and in turn display the same reading as the meter remotely. Pulse connected systems do have their problems. Firstly no pulses can equal no consumption seen in the remote system but this may be normal for a feeder that does not normally consume that much energy, however there may be a fault with wiring or component in the system that goes unnoticed.


Unlike pulses with a more intelligent system where a dedicated communication protocol is used, the meter is asked by the remote system for the readings out of its internal registers. This means that if the meter fails to respond then an alarm can be raised straight away. Not only that but any register/ value in the meter can be read remotely such as current, voltage, power factor, frequency, instantaneous power as well as the energy register displays. The most common protocol in use would be MODBUS however there are others such as M-BUS and BACNET.

Analogues Outputs and Alarms

Some Electricity Meters have analogue outputs which can be programmed to give a 4-20mA or similar in sympathy with the amount of instantaneous power being consumed. Other Electricity Meters have alarm outputs which can be programmed to signal various conditions.

How to choose battery capacity

To have a better usage of the solar system or backup power system, the right battery capacity select is important. Battery selection is according to the needs of the application, voltage, discharge time and temperature are the most basic parameters in the system (need to be determined).

The capacity is related to the battery charge and discharge current: the current increases, the lower capacity; smaller the current, the higher the capacity.

Battery discharge current and capacity has the relationships follow Peukert equation:

            C = I n · t
            C - Capacity (Ah)
            I - Current (A)
            t - Time (sec, min or hour)
            n – Constant value

Following is an example for battery capacity selection in constant current discharge condition:


Load current of 20A
Normal running voltage is DC 48V ± 15% 10% 0 ° C
Can work last 5hours (minimum).

The basic calculations are as follows:

The maximum DC bus voltage U max = 48 × 1.15 = 55.20V
The minimum DC bus voltage U min = 48 × 0.90 = 43.20V
If use the monomers voltage of 2volt battery, U max ÷ 2.25 (float voltage) = 55.20 ÷ 2.25Vpc, = 24.5, total need about 24pcs.
Minimum discharge voltage U min ÷ 24 = 43.20 ÷ 24 = 1.80Vpc only

If the temperature is 25 ℃, from the factory battery specification table shows that: when the discharge termination voltage of 1.8V, GFM-150 type battery 5 hour rate discharge current is 27A.

However, the required use of a temperature of 0°C! Should be carried out in accordance with the manual given formula and the correction factor correction:

The discharge capacity required by: Ct = 20A × 5h = 100Ah
Correction factor: K = 0.018
Capacity after correction: C e = 100 × [1 +0.018 × (0 - 25)] = 182Ah
Requirements of the discharge current (25 ° C, and 5-hour rate): I d = 182 ÷ 5 = 36A

Clearly, GFM-150 batteries can not meet the requirements. From the factory battery specification table shows that: GFM-200 battery 5 hour rate discharge current of 36A, it seems to meet the requirements.

But if need the battery can reliably support system in the entire life span should also be considered in the selection of the battery end-of-life provisions: 80% less than the rated capacity of the battery discharge when mean the end of life.

So the actual discharge capacity should be:

C = 182Ah × 120% = 218Ah
25° C when the discharge current (5 hour rate): I = 218/5 = 43.6A

From the factory battery specification table shows that: when the discharge termination voltage of 1.8V, GFM-250 type battery 5 hour rate discharge current of 45A, to meet the requirements.

Finial correct selection of the battery results: 24pcs GFM-250 type batteries.

Difference of 193 and 192 serie

192 series panel meter are Blue Jay electronic early-type Power Panel Meters, designed from 2004, full series product mass production in 2005, accuracy class is 0.5. In 2007 upgrade the hardware and software, the accuracy is higher than 0.5 class.

Full type have voltage meter, amp meter, active power meter, reactive power meter, frequency meter, power factory meter, energy meter.

Products can use in measure three phase and single phase data.

Standard meter case dimension is 96x96x123mm (mode number 9), 120x120x123mm (mode number 2).

193 series panel meter are new generation of panel meter in Blue Jay electronic early-type Power Panel Meters, designed from 2010, full series product mass production in 2011, accuracy class is 0.2.

With improved outlook, suit for most market all over the world, use more compact case, standard panel size (96x96mm), (80x80mm), (72x72mm), depth only 71mm, can be located in small size electrical cabinet.

Tree-phase active power meter reactive power meter, power factor meter combinative in one meter, can effectively reduce the client's investment. Cancel the DC grid measurement series, focus on AC grid metering.

BJ-194 series multifunction pow

The BJ-194 series Multifunction Power Meter, once cabled and connected is seen to give a correct voltage and current reading, but shows negative values for active power (generation).

This is an error with the cabling for the current transformer secondary; the direction of the transformer current has to be respected as shown in the connection diagram. The current transformers have a two face primary; the current must pass from P1 to P2 giving the result in secondary (S1 and S2) of 5 amps.

The error stems from:

a). The current transformers have been incorrectly installed. As a result it gives the direction of the current as passing from P2 to P1; to resolve this problem, the current transformer does not have to be dismantled and installed again, but the transformer secondary (S1 and S2) just has to be inverted.

b). The connection of the current secondary in the current transformers have been incorrectly connected; to resolve this problem just connect the S1 transformer secondary to the S1 on the meter and the S2 on the current transformer to the S2 on the meter

The BJ-194 series Multifunction Power Meter, once cabled and connected, is seen to give an incoherent Power factor and CosΦ reading (-0.01 or similar).

This is again a current transformer and voltage phase connection error phase A, must correspond to the current transformer installed in phase A; phase B, must correspond to the current transformer installed in phase B; and phase C, must correspond to the current transformer installed in phase C.

This connection is clearly shown on the back of the analyzer.

The BJ-194 series Multifunction Power Meter is measuring in average voltage and is displaying the secondary voltage (for example 110 volts).

Ensure that the voltage Transformer ratio has been correctly set (please refer to the user manul).

The BJ-194 series Multifunction Power Meter does not correctly display the current reading. It shows values varying between 0 to 5 amps of current.

Ensure that the Transformer ratio has been correctly set; once correctly set the current measurement shall be shown correctly (please refer to the user manul).

Maintenace of the power meter

These type multifuction meter does not require any special maintenance. No adjustment, maintenance or repairing action should be done when the instrument open and powered on, should those actions are essential, high-qualified operators must perform them.

Before any adjustment, replacement, maintenance or repairing operation is carried out, the instrument must be disconnected from any power supply source.

When any protection failure is suspected to exist, the instrument must be immediately put out of service. The instrument's design allows a quick replacement in case of any failure.

Auxiliary power:

Blue Jay's Panel Power Meter with universal (AC / DC) power input, Instruments limit work power supply: AC / DC (85-265V), please ensure that the auxiliary power can match for meter to prevent damage to the product.

This type meter have complete over-voltage and under-voltage protection, if your local can not find stable aux power supply, and need to use the power supply for phase to phase voltage, please contact Blue Jay's sales team for 220V/110V transformer power supply, this is anti-harmonic type to prevent frequent trigger over-voltage protection. (in protection trigged, the meter will automatic off power untill user restart the meter manually)

A. Suggest install 1A fuse in the fire line side.
B. For the areas with poor power quality, suggest install lightning surge suppressor and rapid burst suppressor to prevent lightning strikes.