Remote or Auto Restart

Overview

EMIT ETS and Dynamic Control panels can be configured to automate the start and load sequence through settings related to various valves around the skid. If the unit is configured to load automatically, it can also be configured to be started remotely and/or automatically restart on certain faults. This document describes the sequence and configuration for these scenarios. A separate document “DC Valve Setup Guide” covers each valve setup individually. Note that navigation to setup screens are listed in this document for the DC panel. The ETS panel has similar screens under Annunciator Setup.

Requirements

Valves: The unit needs at least an automated suction, blowdown, and recycle/bypass valve. The suction valve can be a block valve, a Suction PID loop on a proportional suction valve, or both. Similarly, there can be an on/off recycle valve or a proportional recycle PID valve.
1. On/off type valves can optionally have a limit switch for open/closed. These are the recommended type for safety reasons.
The purge sequence should be set up, along with other important start parameters (detailed below)
1. This is not strictly required. Instead, the unit can be purged manually and then the unit can be restarted remotely without blowing all the way down.
The maximum number of remote resets must be more than 0
There should be a panel buzzer on the Brain “HORN” output. Ideally a larger external horn or siren is placed on the skid and wired to this input (if needed, through a relay) to help warn users when the unit is about to start
It is recommended that warning signs be posted that unit can start remotely

General Sequences

Start Sequence

Unit is stopped by local or remote action, and speed switch is in AUTO position.
1. Blowdown, suction block, discharge block valves are closed
2. Bypass may be open or closed based on configuration on “Bypass Logic” screen
3. Recycle (if used) is open, and suction proportional valve (if used) is closed. This depends on the PID setup.
Modbus request for “remote reset” is received, or ‘remote reset’ input is activated
1. If the [number of remote starts] < [max number of allowed remote starts], and [number of auto restarts] = [max number of auto restarts], the unit can start. Note that the max number of auto restarts can be zero, and a remote restart is still allowed.
2. Note that someone could also press reset then start on the panel locally, and the sequence from here on would still be the same. A ‘local’ reset by panel button press resets the current number of remote starts to zero
If the suction pressure is above the blowdown limit, a blowdown is performed
1. The blowdown opens until the pressure is under the limit
2. If the “max blowdown time” is reached before the blowdown pressure is reached, the sequence will fault out (usually because the valve is not working)
If the suction pressure is below the purge limit, a purge sequence is performed
1. The full sequence is shown on the purge setup screen
2. The suction will open during the sequence, along with bypass and blowdown at times to get the system purged out
3. When purge is complete, the suction and blowdown will again be closed, and bypass left open
The pre-lube sequence is run
1. If the purge sequence did not need to run before pre-lube, and the bypass is closed for some reason, it will open during pre-lube
The system moves to ‘Ready to Start’
1. Suction and discharge block valves are opened (if used)
2. For EMIT engine controls, the auto-crank sequence will start
3. For non-EMIT engine controls (e.g. CAT ®), the engine control unit will be sent a signal to start and the fuel valve opened
Once engine is running, the state moves to the ‘running state’
1. Independently, the idle hold condition will hold the unit at idle until the condition is met, e.g. oil temperature, at which time the unit goes to normal running speed(s)
Once idle hold condition is met, the load delay timer begins counting down
Once the load delay expires, the bypass valve closes
1. Typically, if a recycle PID is used it will be set to activate after load delay ends, so it would start to close at this time as well.
2. Assuming process pressures are on ‘C’ class alarms, they will arm when the pressures rise.
3. A max ‘C’ timer can be configured so that the unit will stop if some amount of time passes and the ‘C’ inputs still have not cleared
Unit is on line

Normal Stop Sequence

Operator presses ‘Stop’ button, a Modbus stop is received, or the “remote stop” input is activated
Unit goes to “Shutdown Delay” state
1. Suction and discharge block (if used) are closed
2. If engine (through CAT panel) is configured to cool down, the cooldown time will elapse
Once unit stops running, bypass is opened or closed based on bypass config for condition after normal stop
Post lube runs
State is “Manual Stop”

Fault Stop Sequence

Some input causes a fault
Unit goes to “Shutdown Delay” state
1. Suction and discharge block (if used) are closed
2. No cooldown is performed, engine is stopped immediately
Once unit stops running, bypass is opened or closed based on bypass config for condition after faulted stop
Post lube runs
If the fault condition calls for an auto restart, and it is possible to auto restart*, the state will go to ‘Auto restart pending’ and start counting down the timer to auto restart
1. Optionally, the unit can blow down at this point to allow some time for the pressure to settle before the next start attempt
2. Once the auto restart timer expires, the start sequence will begin at #3 of the start sequence above
If an auto restart is not applicable, the unit goes to Faulted state

Conditions to allow for an auto restart

For an auto restart to take place, all the following conditions must be met:

The unit must be in ‘auto’ switch position
The number of auto restarts currently attempted must be less than the maximum allowed number of auto restarts (which by default is zero, for no auto restarts)
The fault that occurred has to allow for an auto restart. This includes low or high suction, low or high final discharge, or one of the user-selected DI faults.

Sequence Setup Notes

Suction PID

If a proportional suction valve is installed, it will be set up as a normal PID loop and given a name “SUCTION”. The activation criteria should be set so that the loop is active when the RPM is above 0, so that when the unit is off the valve is closed. Once the unit is turning the PID loop will come on and try to keep suction at the set pressure. The output value for “inactive” should be set to whatever closes the valve.

Note that during the purge sequence the valve position will be overridden by the needs of the sequence. As soon as purge ends the PID loop goes back to normal.

Recycle PID

If a proportional recycle valve is used, it will be set up as a normal PID loop or can be set up at the special “Dual input recycle PID” under outputs setup. If using a normal PID, the activation criteria is recommended to activate right after load delay ends, and when inactive have the valve open.

On / Off Valves

For on/off valves (suction block, discharge block, bypass, blowdown) the valve setup is at Settings -> Brain -> Outputs Setup -> Output to Valve selection. See Annunciator_Valve_Setup

Purge / Blowdown thresholds

The suction pressure limits for purge / blowdown are found at Brain -> Outputs Setup -> "Purge Threshold" and "Blowdown Settings".

See Annunciator_Blowdown_Setup and Annunciator_Purge_Setup.

Load Delay

The load delay can be set at Brain -> Timers Setup -> Load Delay Timer. The C contacts can be unarmed during load delay to prevent incorrect shutdowns. See Annunciator_Load_Delay

Bypass Logic

A few aspects of the bypass valve logic can be adjusted at the page Brain -> Outputs Setup -> Bypass Logic. See Annunciator_Bypass_Setup

Misc Start Permissive

Optionally, an extra start permissive can be added at Brain -> Outputs setup -> Misc Start Permissive. This can come from any input and can add some extra condition that has to be met to allow the unit to start locally or remotely.