E-Stop manual reset button

[TurpoUrpo]

I was not asking about color if that was meant for me.

 

[nonuke]

I was not asking about color if that was meant for me.

No, It wasn't for you. I was just giving my opinion.

 

[Geospark]

Safety RESET Indicator Light

TurpoUrpo,

I did wonder about the colour, as you didn't say, but I was sure you were well aware that it should be, and is BLUE, and that's why you didn't mention it. Either way, I've added it into your description below for clarity...

What do you think Geospark. For safety circuit reset button, we have one system with (BLUE) off = ok; flashing = tripped, not ok to reset; light up no flashing = tripped, ok to reset.

You have to decide whether this setup meets, or exceeds the recommended standards?

Let's break it down...

The fact that this is an illuminated pushbutton automatically means that both the pushbutton and indicator colour are the same. However, for the sake of clarifying both the pushbutton and indicator requirements, we will deal with the two functions separately.

Pushbutton:
Is it for a mandatory action?
Is the BLUE mandatory action colour used?

Indicator light:
Is it to indicate a mandatory action is required?
Is the BLUE mandatory action colour used?
Does the indicator light turn ON when the mandatory action is required?
Does the indicator light turn OFF when the mandatory action is no longer required?

If you can answer yes to all of the above, then the minimum recommended standards in EN 60204-1 are satisfied.

Ok then, let's move on...

 

[Geospark]

Flashing Indicators

You also have a flashing function incorporated into the safety RESET's indicator light.

Flashing of indicator lights is covered in EN 60073.

So let's take a look at what it says...

Note: To clarify - the term actuator means, among other things, a pushbutton actuator.
Any comments in italics are mine.

EN 60073:2002 Basic and safety principles for man-machine interface

Extract from the preface...

Supervision and intervention are the principal tasks of personnel engaged in the monitoring and control of equipment or processes.

Indication for the representation of conditions, and actuating devices to enable intervention under normal and fault conditions, are essential to this purpose.

The information presented should meet the needs of the users for the monitoring and control tasks which they are required to perform, for example, in extensive industrial processes.

Safety and ergonomic aspects should also be taken into account. The use of only a single means of coding is often insufficient to ensure unambiguous representation of information.

Apart from an unambiguous marking of the indicating and actuating devices, there is a requirement for a clear and consistent system of coding.

E.g. If you recall, I mentioned earlier about not wanting to have different colour coding for the same type pushbutton (CYCLE) based on whether it was used for a normal or abnormal condition. This would create unclear and inconsistent coding. That's why I suggested labeling the abnormal condition pushbutton something more appropriate.

The choice of code will depend on the information which it is intended to impart. This may relate to the state of equipment (or part of it), to the condition of a process, and/or to the effects which this condition has on persons, property and the environment.

The user is required to decide on which of these criteria the coding for the relevant application is to be based.

Of those three information types, the "state of equipment" applies to the RESET indicator light.

4.2 Visual codes

Colour and changing of elements over time (flashing) are the most effective visual means of attracting attention. Therefore these codes shall be used with consistent meanings; colours for giving priority and flashing for attracting attention.

The initial flashing of the RESET indicator light attracts the operator's attention, so this is fine.

4.2.3 Coding by changing of characteristics over time

4.2.3.1 General

A steady light is used for giving information.

The RESET indicator light changing from flashing to steady provides a form of information, so this is ok.

To attract attention, and especially to give additional emphasis, a changing of characteristics (flashing) may be used, for example, for the following purposes:

a) to request immediate action (see note);

b) to indicate a discrepancy between a command state (or an indicated state) and the actual state of the related equipment;

c) to indicate a change of state (flashing during a transition period).

Note: When a flashing annunciator, for example, is acknowledged by the operator it becomes steady.

The RESET indicator light initially flashes to attract the operators attention and inform them that an immediate action is required. The action required does not have to involve the flashing annunciator itself, it is just an indicator light. Once the action required is complete, say closing a safety gate interlock switch, the indicator light changes from flashing to ON, informing the operator that a state has changed i.e. the safety device is ready for RESET. Upon pressing the RESET, the light turns OFF, indicating the mandatory action is no longer required. So all this is fine.

Further thought has to go into the flashing though...

4.2.3.2 Frequencies of flashing visual characteristics

Two flashing frequencies, f1 and f2 are recognized. The information with the highest priority shall be associated with the higher flashing frequency used in the case concerned (e.g. f2: alarm given; f1: the cause of the alarm cleared).

The flashing frequency f2 should be used for the RESET indicator light.

The permitted ranges for flashing frequencies are the following:

- f1: slow flashing, 0,4 Hz to 0,8 Hz (24 to 48 flashes per minute);

- f2: normal flashing, 1,4 Hz to 2,8 Hz (84 to 168 flashes per minute).

The normal flashing frequency f2 should be within this range.

Where only one flashing frequency is used, it shall be f2.

The ratio f1:f2 of the flashing frequencies shall be constant for a given application and shall be at least 1:2,5 but not more than 1:5. A ratio of 1:4 is recommended (for example the frequencies 0,5 Hz and 2 Hz).

This ratio ensures there is a distinguishable difference between a slow flashing f1, and fast flashing f2 frequency for indicator lights close to each other.

It is recommended that the PULSEAUSE ratio be about 1:1, the ON time of the light should be about equal to the OFF time. For f1, the PULSE may be longer than the PAUSE; for f2 the PULSE may be shorter than the pause. However, for f1, the PULSEAUSE ratio of 2:1 and, for f2, the PULSEAUSE ratio of 1:2 shall not be exceeded.

The recommended ON:OFF flashing of the indicator light should be about 1:1, this is best for critical or important information. When it's not as critical, but more a warning alarm, the ON is better to be short and the OFF slightly longer, but not OFF more than twice as much (1:2). I prefer 1:1 for critical alarms, and 1:1,5 for warning alarms.

5.2.1.6 RESET actuators

RESET actuators (used, for example, with protective relays) shall be BLUE, WHITE, GREY or BLACK, except RESET actuators which also act as STOP / OFF actuators. The colour of such STOP /OFF actuators shall be in accordance with 5.2.1.2.

The RESET is a mandatory action, so BLUE must be the choice here.

5.2.2 Illuminated actuators

5.2.2.1 Types

Distinction is made between the types of illuminated actuators according to the colour displayed by the illuminated part of the actuator.

Type a - Actuators which have the same colour whether or not they are lit.

The RESET is type a.

Type b - Actuators which have a single colour when lit that is different from the colour when not lit and both colours have meanings.

Type c - Actuators which have more than one possible colour of lighting, for example, to indicate different conditions, but the colour when not lit is without meaning.

Note: Lamps which are used as signal lights, but which are designed to be pushed for testing the lamp, are not considered as illuminated actuators.

5.2.2.3 Modes of use

5.2.2.3.1 For actuators of types a and b, the following principal modes of use are distinguished as follows:

a) Indication

An actuator is lighted to show the operator that he may or should operate the lighted actuator or, in certain applications, that he should perform a certain task and then operate the actuator. Receipt or execution of the order (which has been given by operating the actuator) is confirmed by the extinction of the light or change e.g. in the colour code or supplementary means of coding (for example, time).

Again, the light flashing alerts the operator to the required mandatory action. Once the action is completed, it may be indicated by a change using time. Time meaning changing of characteristics over time i.e. flashing.

Sequence: First actuator lights up, then the operator operates the actuator. The colours WHITE, YELLOW, GREEN or BLUE shall be used in this mode.

While not stated here in the sequence, from the previous paragraph, it was stated that, in certain applications, the operator may, or should perform a certain task and then operate the actuator.

Note 1: A flashing light may be used to attract the attention of the operator, for example, in the case of an alarm. When used in such a way, the operation of the actuator may change the flashing light into a steady light. The steady light then remains on, until the cause of the alarm has been eliminated by a separate action. In addition, the actuator may have the function specified in table 9.

Again, while not stated here, you may likewise change the flashing light into a steady light after carrying out a separate mandatory action, and then press the indicator light RESET.

Finally...

 

[Geospark]

Is BLUE for Safety RESET? or Safety RESET must be BLUE?

b) Confirmation

When an unlighted actuator has been operated, it lights up as a confirmation that the order (given by operating the actuator) has been received or executed. It remains lighted until a contrary order follows.

Sequence: First operate the actuator, then the actuator lights up.

The colours WHITE, YELLOW, GREEN or BLUE shall be used in this mode.

Note 2: Illuminated actuators may be used with a flashing light in order to give a "stepwise confirmation". When the unlighted actuator is operated, the light begins to flash confirming that a starting operation, or sequence, or a transition period has been initiated. When this has been completed, the light automatically changes to a steady light or is unlighted to confirm that normal running conditions have been established.

b) Confirmation, and all beneath it, refers to normal START / DELAYED START or STOP / DELAYED STOP type illuminated pushbuttons where they either come ON steady, or flash until the action is complete. Some of these may be mandatory actions and so BLUE must be used. This is important to point out, as some may think that BLUE illuminated pushbuttons are the reserve of safety RESETS only. That notion should not be entertained. All mandatory action pushbuttons, indicator lights or illuminated pushbuttons, must be BLUE.

TurpoUrpo,

The simple answer, of course, was that the setup you outlined is fine, and in my opinion it exceeds the basic standards required by adding an extra level of information for the operator. The reason I go the long winded route is to show exactly how you would go about reasoning it out.

I hope that answers your question and educates you a little more on the flashing aspect.

Regards,
George

 

[TurpoUrpo]

Yes thank you, this was very good. You assumed right, button is blue And that is what i tought, but i wanted to confirm it little more, i knew you would give very thorough answer.