Pulse meter commissioning and reconciliation

A pulse meter connection is commissioned when four things agree: the meter's output circuit and the counter input, the pulse weight, the counter's capture rate, and the cumulative count against the meter register. This guide takes you through each check in order and ends with an acceptance record that you can keep with the site documents.

Download the acceptance record (.txt). Print it, or fill it in on site.

Identify the output circuit

Read the installed meter's manual and terminal diagram, and record:

• the output type: dry contact, open collector or open drain, or a powered voltage output;
• the terminal numbers and the polarity, for a transistor output;
• the maximum voltage and current of the output, and its isolation;
• the pulse width and the minimum gap between pulses.

Then check the counter input against those values: the sensing voltage that it supplies or accepts, its polarity, and its timing limits.

Swipe to see the whole drawing

The dry pulse vs active pulse guide explains each output type and what the counter needs for it. An S0 label or a two-terminal symbol describes the connection only in part, so always compare both specifications. Use an approved isolator or interface where the two do not match.

Record the pulse weight

The pulse weight tells you what one pulse represents. It can be written as pulses per kWh, litres per pulse, pulses per cubic metre or in another form, and many meters let you configure it. Read the value from the installed meter's display or menu, record it with its units and the date, and photograph the meter nameplate. An old drawing can describe a meter that was since replaced or reconfigured.

Keep the raw count as well as the converted total, so that you can correct a scaling error later without losing the evidence.

Check the maximum pulse rate

Calculate the pulse rate at the maximum credible load, not the average. For electricity:

pulse rate (Hz) = maximum power (kW) × pulses per kWh ÷ 3600

A 72 kW circuit on a 1,000 pulses/kWh output produces 20 Hz, a 50 ms period. With a 20 ms pulse, that leaves a 30 ms gap. The ZPC-2X accepts up to 40 Hz with at least 10 ms on and 10 ms off, so this connection is inside its limits:

Also calculate how many pulses arrive in one reporting interval. At low load a meter can send only a few pulses per interval, so a short-interval rate looks stepped even when the cumulative total is right.

Check counter rollover

A counter with a fixed number of bits returns to zero after its maximum count. Check how long that takes at the maximum rate, and make sure the receiving system handles the rollover:

A 32-bit counter at 72 kWh per hour and 1,000 pulses/kWh runs for about 2,486 days (6.8 years) before it rolls over. A 16-bit counter on the same meter rolls over in 55 minutes, so check the width of every counter in the path.

Test counting with known pulses

1. Record the meter register and the remote raw count at the same time.
2. Produce or observe a known number of pulses: a controlled load, a test signal where the procedure allows it, or a period of normal consumption.
3. Confirm that the raw count changed by exactly that number.
4. Convert the change with the recorded pulse weight and compare it with the change on the meter register.

For a dry contact, check that one closure counts once. Contact bounce can produce several counts per closure; the counter's filter must reject bounce and still accept the shortest valid pulse. For a transistor output, check the polarity and the voltage at both states.

Test power loss and recovery

Pulses continue while the network is down. Prove what the counter keeps:

• through an interruption of the wireless network or the upstream connection;
• through a Gateway restart;
• through a power interruption of the counter, where the product supports it and the test is safe.

The receiving system must not add a retransmitted cumulative count twice. A cumulative counter and a series of interval values are different data contracts. Record which one the system uses.

Reconcile with the meter register

Choose a period long enough to include many pulses: at least several hundred, and more at low resolution. Record the meter register and the remote total at the start and the end, at known times. Compare the two changes. The difference should be within one pulse weight plus the reading resolution.

Investigate any larger difference before you apply a correction factor. Common causes are a wrong pulse weight, a transformer ratio applied twice, missed pulses at high load and double counting from bounce.

Repeat the reconciliation after any change to the pulse weight, the meter, the counter's configuration or firmware, or after a suspected reset. For billing, the source meter and its approval remain the reference.

Acceptance record

Keep one record for each pulse connection. The downloadable template has these fields:

Use the pulse meter application guide for the complete system, or build a system from the meter output and rate.