1. Low current alarm appears/display shows LoI what does it mean?

Ans: When Low current alarm occurs, it indicates that the load is low, usually this is not an indication of an error. Turn on the loads and wait for 5 seconds and the alarm will reset.

2. What should I set for target power factor?

Ans: The recommended target power factor to set is 0.95 inductive. This is an optimum setting to avoid over compensating.

3. What should I set for reconnection time?

Ans: The purpose of reconnection time is to protect the capacitor and contactor from maximum inrush current. This will occur when the capacitor is charged to the minimum voltage while the contactor switch is in at the highest peak voltage.

4. How do I verify that the power factor capacitor is malfunctioning

Ans: Use a clamp meter to measure the AC rms current on the capacitor. Turn on the particular step manually. The capacitor might be spoiled if there is no current being measured.

Technical Question regarding CT

What is the class for Mikro relays?
1. Mikro relay's accuracy is measured in terms of percentage. The standard value is +/-5%
2. Class classification is reserved for Current transformer which is detailed in IEC60044-1
3. There are 3 types of protective class classification of CT accuracy which is
- Class P (protection)
- Class PR (protection low remanence)
- Class PX (protection for low reactance)
4. Standard value for protection class CT is 5 and 10
5. 5 for +/-1% and 10 for +/-3%
6. 5P10 means maximum 1% deviation from nominal value at 10 times of rated current
7. There is also measurement type current transformer
8. Standard value for measurement class CT is 0.1, 0.2, 0.5, 1, 3 & 5

The ANSI standard for CT is ANSI C.57.13, other standards as listed below

British: BS 3938 & BS 7626,
German: DIN VDE 0414-1,
Australia: AS 1675
India: IS 2705.


How to calculate TNB power factor penalty

The following is an excerpt from the TNB Tariff Book.

For all Tariffs, except Tariffs A and G, the consumer should strive to obtain the highest Power Factor possible in the operation of any of his electrical installations. If the Average Power Factor in any month is found to be:

1. Below 0.85 and up to 0.75 lagging, a supplementary charge of one and one-half per cent (1½%) of the bill for that month for each one-hundredth part (0.01) below 0.85 and up to 0.75 lagging Power Factor will be added to the bill for that month, and
2. Below 0.75 lagging, in addition to the charge payable under subparagraph (A) above, a supplementary charge of three per cent (3%) of the bill for that month for each one-hundredth (0.01) part below 0.75 lagging Power Factor will be added to the bill for that month.

Example: A Consumer has a Power Factor at 0.60 and his consumption is RM4,800.00
(a) 0.85 - 0.75 = 1½% x 10 units lagging = 15%
(b) 0.75 - 0.60 = 3% x 15 unit lagging = 45%
Total extra levied = 60%

Therefore, his penalty charge would be 60% of RM 4,800.00 which is RM 2,880.00

The total payable will hence be RM 7,680.00


FAQ for Overcurrent EarthFault

1. What is timer multiplier

Ans:When there is a requirement for up stream down stream protection, we want both relays to have the same characteristic curve. The down stream relay protection should always be faster in tripping time then the up stream. This is achieved by setting the time multiplier setting. Setting the time multiplier to a smaller value causes the relay to trip faster.

2. Can the MK201A be used for 3 phase 3 wire systems?

Ans: Yes


FAQ for Voltage Relay

1. Disabling under voltage protection in MU 2300 click here.

2. Broken neutral protection click here.


FAQ for Earth Leakage Relay

1. Notification!! Changes in ZCT click here.

2. ELR and ZCT specifications click here.


FAQ for Earth Fault Relay

1. Three phase three wire connection for MK201A Earth Fault Relay here.


FAQ for Metering Solutions

1. Three phase three wire considerations click here.