Your TNB Bill Has Five Lines. Your Panel Still Has One Meter.

Since July 2025 a Malaysian electricity bill has been itemised into five charges. The switchboard behind it still reports one number. That gap is where savings disappear.

A medium-voltage factory in Peninsular Malaysia does not pay one rate. It pays four, plus a fuel adjustment revised monthly.

Energy — 29.83 sen per kWh. Capacity — RM29.43 per kW of maximum demand. Network — RM59.84 per kW. Retail — RM200 a month. AFA — 3.61 sen per kWh in October 2026.

The two demand lines together come to about RM89.27 for every kilowatt of your highest 30-minute average in the billing month. One compressor restarting at 14:05 can set that figure for four weeks.

Low-voltage premises pay 50.68 sen per kWh all in — 27.03 energy, 8.83 capacity, 14.82 network — plus RM20 a month, so the bill rises in a straight line with usage.

02 · Measurement point

A cash register cannot diagnose a plant

The incoming meter is a cash register, not a diagnostic instrument. It sees every load added together and reports the sum. When the sum rises, nothing says which part moved.

One point of measurement is being asked to answer a question that needs six.

A factory’s consumption rises 14%. Maintenance checks the chiller, finds nothing, calls it seasonal. Months later a compressed-air leak is found at a flange — running eight hours a day for most of a year, invisible on the incoming meter because it never moved the total enough to look abnormal.

Submetering does not find the leak. It makes the leak visible as a column that climbs while the others stay flat.

The rule is not "meter everything": meter wherever responsibility changes, or where a load can be acted on independently.

Two constraints decide the count: every point needs a Modbus address and a route back to the gateway, so empty panel space and spare conduit are real costs; and a meter on a circuit nobody will act on produces data, not savings. Start with six to twelve points.

Commercial buildings use the same points under different names.

The requirements are modest but specific: three-phase measurement, a demand register with a timestamp, time-of-use registers that match the tariff bands, and a readable port.

The
DTSD1352-C
covers that set. It measures voltage, current, active, reactive and apparent power, power factor and frequency, with voltage and current accuracy of ±0.2% and power accuracy of ±0.5%. Active energy is Class 0.5S to IEC 62053-22, reactive energy Class 2, and harmonic content is available to the 31st order plus total harmonic distortion.

The demand register is what matters for a TNB bill. The meter records four kinds of maximum demand — forward active, reverse active, inductive reactive, capacitive reactive — with the time each occurred. Its demand cycle defaults to 15 minutes with a one-minute sliding window. TNB bills on a 30-minute average, so the cycle has to be set to match before the two numbers can be compared; this is a commissioning step, not a factory default.

Time-of-use registers support four time zones, eight interval lists and eight tariff rates — enough to separate the 14:00–22:00 weekday peak from off-peak. It keeps 48 months of monthly frozen data and 90 days of daily, so a year-on-year check does not depend on someone exporting a report.

Communication is RS485 Modbus-RTU at 1200–19200 bps, addressable 1 to 247. There is one optocoupler input, one relay output (AC 220V / DC 30V), and support for three external NTC sensors.

Voltage ranges include 3×240/415V — Malaysia’s low-voltage three-phase supply — alongside 3×220/380V, 3×380V, 3×100V and 3×57.7/100V. Current input is 3×10(80)A direct, or 3×1(6)A and 3×10(100)A through CTs. Mounting is DIN rail. CE marking covers EMC and LVD, with an IEC 62052 / 62053 declaration on file.

Where points are dense — a row of outgoing feeders in one cabinet — the
DTSD1352-4S
puts several circuits into one DIN-rail unit.