We've just taken delivery of a control panel that has switches controlling power to two pumps, a 9kW tank heater and an over-temperature trip. The control voltage is all 230V. Our maintenance engineer says that the control voltage, according to EIC 60204, should be stepped down to 24V. Is this mandatory? The panel is fully enclosed with an interlock cutting power when it's opened. There are no complex plc's involved, all very simple controls.
The maintenance engineer is quoting Section 9.1.1 of the standard, that "where control circuits are supplied from an AC source, transformers having separate windings shall be used to separate the power supply from the control supply".
Clause 9.1.1 has the following statement:
Exception: Transformers or switch mode power supply units fitted with transformers are not mandatory for machines with a single motor starter and/or a maximum of two control devices (for example, interlock device, start/stop control station).
The maintenance engineer is quoting Section 9.1.1 of the standard, that "where control circuits are supplied from an AC source, transformers having separate windings shall be used to separate the power supply from the control supply".
Clause 9.1.1 has the following statement:
Exception: Transformers or switch mode power supply units fitted with transformers are not mandatory for machines with a single motor starter and/or a maximum of two control devices (for example, interlock device, start/stop control station).
I would further ask what circuits are classified as "control circuits" for this panel?
Certainly the temperature trip is ... plus the inputs to the contactors (based on what, switched/controlled from where ???), but sounds like the pump and heater wiring are actually "power circuit" ?
Because of the Supply of Machinery (Safety) Regulations and Section 6 of H&S@W etc. Act, I would be inclined to discuss any queries about conformity with the supplier and manufacturer in the first instance.
Thanks gkenyon.
But the panel has 2 start/stop buttons for pump motors, an activation switch for a temperature controller, and an overtemperature interlock. Doesn't this preclude that exception?
But the panel has 2 start/stop buttons for pump motors, an activation switch for a temperature controller, and an overtemperature interlock. Doesn't this preclude that exception?
The problem is that you are asking for an interpretation of the standard in the particular circumstances. Only a Court of Law can interpret a standard.
Engineers can only provide a professional opinion - and even then, would need full facts, not just a discussion in a Forum.
The question you ask, suggests that either yourself, and/or a colleague, have interpreted a standard in a particular way (although in a different way to the interpretation provided at the start of this thread which mentioned effectively ELV at 24 V), whereas in fact the manufacturer has interpreted it in another way.
Yes, these differences need to be sorted out ... but without speaking with the manufacturer and engaging in dialogue, the only way to move this on is to involve legal professionals, because even if you were to get someone in this forum to agree with you, the manufacturer (who actually makes the legal declaration) appears to have a different view and they may well stand by that.]
To consider one possible outcome ... if you and the manufacturer don't agree, and the manufacturer refuses to make any changes, yourcompany decides they will make the changes (to avoid legal action or returning the product etc.) ... which makes your company responsible for the safety of the Machinery (in its entirety perhaps) going forward ... which in itself would not be sensible without taking legal advice ... and the legal advice might be to sort it out properly with the manufacturer at this stage ?
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