5.2.12 Current Transformer
The current transformer is used to measure current for use in energy estimation calculations and heater health diagnostics. The current transformer fault detection algorithms must be synchronised to the output demand. The CT source identifies which output is responsible for switching current through the load. It is valid only for logic or relay outputs. DC Outputs cannot be used with this facility.
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P31 |
Select P31 to configure the Current Transformer Source.
Note: the output mnemonic in the following list will only be shown if the output is configured for control. |
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CT alarms include:- Load current Leakage current Over-current The threshold values are set in Level 2. |
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none |
Load diagnostics and alarms are not generated. The values for load and leakage current will follow the instantaneous current read via the CT. This can be useful to allow an 'indication only' reading of current (default). |
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oP1 |
OP1 Function linked to output 1
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oP3 |
OP3 Function linked to output 3. This must be a relay output. |
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oP2 |
OP2 Function linked to output 2. This is a relay output. |
oP4 |
OP4 Function linked to output 4 |
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P32 |
Select P32 to configure Current Transformer Range. The CT input is designed to accept signals in the range 0-50mA. An external current transformer is required to step down the switched current to this range. The range should be set to the nominal rating of the electrical load. Only available if the CT option is configured by P31. |
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Default 100.0 |
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10.0 to 999.9 amps |
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P33 |
Select P33 to configure Current Transformer Alarm Latching.
Latching alarms retain the alarm state until acknowledged by the operator. There are three CT alarm types (Leak, Load and OverCurrent) which all share the same configuration. A current alarm may be attached to AL1, AL2 or AL3 using P37.
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Latching alarms are described in section 4.3.5 ‘Alarm Latching’. The CT alarms may be attached to AL1, AL2 and AL3 using the parameter P37. This is described in section 5.2.14. |
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none |
Non Latching alarms clear automatically when the condition causing the alarm clears, and require no operator intervention (default). |
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AUto |
An automatic latch may be acknowledged at any time. The alarm will reset immediately after the alarm has been acknowledged and the measurement has returned to the safe state. |
Nan |
A manual latching alarm may only be acknowledged after the fault has been repaired and the measurement has returned to the safe state. Manual latching alarms prevent the alarm from being reset before the measurement is repaired. |
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