The indicator lamps and the buzzer on the control cabinet are the interface an operator touches most often. When an alarm comes up, what it means, whether it can be reset straight away and whether the machine can be started again all depend on which kind of alarm it is. The protection configuration of the ZYD-100 includes overpressure alarm with sound and light and shutdown, phase loss and sequence protection, and infrared level and foam detection with automatic de-foaming, and the conditions that trigger these actions are not the same, so the way they are handled is not the same either.
Alarms fall into three kinds
The first kind is the acting alarm that stops the machine. The overpressure alarm with sound and light and shutdown belongs here: when the pressure exceeds the set value the machine stops and gives an audible and visible signal. Infrared level and foam detection triggering automatic de-foaming follows the same logic, both intervening actively once the state of the machine has already moved away from the normal range. The second kind is the warning that does not stop the machine but needs a person to act on it, such as the phase loss and sequence protection indicating abnormal supply conditions. The third kind is recorded without any action, and is normally a maintenance reminder.
| Kind | Typical source | State of the machine when it triggers | What to check first |
|---|---|---|---|
| Acting | Overpressure alarm with sound and light and shutdown | The machine stops with an audible and visible signal | Whether the element resistance has risen or the pump output has fallen |
| Acting | Infrared level and foam detection with automatic de-foaming | Automatic de-foaming intervenes or the oil inlet is blocked | The level in the chamber and whether air is being drawn in with the oil |
| Protection | Phase loss and sequence protection | Starting is not permitted, or abnormal supply conditions are signalled | The phase sequence and any broken line in the site distribution |
| Warning | Motor overload operation | The circuit is disconnected | Whether the load has exceeded the set value |
| Warning | Maintenance and consumable reminders | Running is not affected | Arrange the servicing according to the records |
Do not reset immediately after a stop
After an acting alarm has stopped the machine, the most instinctive reaction is to press the reset and start again. In most cases that is the right thing to do: if the overpressure protection has tripped and the differential pressure has already fallen back into the safe range, the machine can be reset and started. But if the cause is still there, resetting only produces the same stop once more, and every restart means going through the temperature build-up, the vacuum build-up and the flow build-up all over again, and the output lost in that period is output thrown away.
- Overpressure stop: look at the differential pressure first and decide whether the element resistance has risen or the pump output has fallen, and only then change the element or check the pump.
- Level or foam action: check the level in the chamber and the inlet pipework and confirm that no air has been drawn in.
- Phase loss or sequence protection: check the site distribution rather than trying it by resetting repeatedly.
- Before resetting, write down the readings at that moment, including the temperature, the pressure and the vacuum level.
Keep the alarm records
A single alarm is an isolated event, and it is the record over several weeks that is the basis for judgement. Four items are worth recording: what the alarm was, when it happened, the oil temperature and pressure at that moment, and what was done about it. These records are not complicated, but they answer far more questions when looked back over than memory does, such as whether a particular alarm only appears when a specific batch of oil is being processed, or whether it clusters into the same part of every day.
Only when these records are placed next to the records of differential pressure, element changes and pump oil changes does it become clear whether the state of the machine is improving or deteriorating.
The alarm lamp tells you the machine has stopped; only the record tells you why it stopped, and handling only the first half means the same thing happens again.
