No. Under no circumstances allow this to be done. This will damage the microprocessors in the meter.
No. All meters normally have a pulse output, but it will be an “SO” pulse output not suitable for a management system. The correct pulse for a BMS system would be a volt free optically isolated pulse.
No. Meter manufacturers have their own constants and therefore a different pulse output value.
The current transformers must be fitted and connected in the correct way or the meter will not be accurate. The current transformers are marked on two sides: ‘P1’ and ‘P2.’ ‘P1’ must face the mains side and ‘P2’ must face the load side. ‘S1’ must be connected to the main side of the meter and ‘S2’ to the load side. Refer to appropriate wiring diagram of the meter for correct connections.
This depends on the ‘VA’ burden of the meter, the cable being used between the current transformer and the meter and the distance the current transformer is from the meter.
Please see current transformer graph for further help.
To accurately measure kWh we recommend a minimum class of 1.0; class 0.5 is better.
A moulded case current transformer is a solid ring of steel in a plastic or resin case and can only be used when you fit the cable through the hole in the middle of the plastic/resin case.
A split core current transformer is manufactured with the steel core in two pieces. This enables the core to be separated, allowing you to fit the cores around the cable without disconnecting the cables. The disadvantage with split core current transformers is that they can be larger than standard moulded case and the price is approximately four times more expensive.
The current transformers should ideally be about 80% of the normal running load, thus allowing a 20% allowance of increasing the load in the future.
No, it is not a requirement but in offices and large warehouses it is recommended.
A direct connected meter is where the current carrying cables are connected into the meter terminals and is normally used up to a maximum of 100 amps.
The correct way would be to have a four pole circuit breaker as the main isolation to the meter with three lower rated fuses to protect the electronics in the meter. The current circuit should have a shorting test block (ATB 23008) that allows the current transformers to be shorted out should the meter need to be removed in the future. Please see our full meter assembly with metal enclosure.
Check that all the cables have been connected into the correct terminals by referring to the connection diagrams in the installation manuals. Check that you have three line voltages present at the meter by referring to the line voltages on display in the meter.
If you have a current transformer-operated meter check that the meter has been programmed to the same ratio as the current transformers. Check the current transformers have been placed on the cable /bus bar the correct way with P1 facing the mains. Check the circuit diagram.
Normally, yes. But you must check with the supplier of the meter.
Please check with the supplier of the meter
Yes, you must use the same current circuit as the line voltage. For example, line 1 voltage must be line 1 current circuit.
Yes. In all cases the ratio of the current transformer must match the ratio of the fitted meter. For example, a meter with ratio 200/5 amp will require a CT with ratio 200/5 amp.
A CT shorting block is used to enable the meter to be taken out of service at a later date. It is good practice to fit one where a current transformer operated meter is being used. It allows the current transformers to be shorted out when the meter has been removed.
Yes, under no circumstances leave a current transformer open circuit when power is on.
No. Although you will need to check with the meter supplier because some meters must not have a common earth on the current circuits.
The fuses in the SX enclosures are 250 volt, 2 amp anti-surge, 5 x 20mm. The Farnell part number is 9922270.
Yes, all you need to do is supply a drawing and we will advise a price and approximate delivery date.