Hand Trip Control Vs Touch Screen Control

[JimmyJunior]

Hello:

We are in the process of upgrading our relaying system at our main substation. We are replacing all of our Westinghouse/ABB electromechanical relays with SEL relays + a SCADA system.

One modification that has caused concern is the replacement of the individual 15kV air circuit breaker operating switches (open/close/lockout)with a Human Machine Interface (HMI). The HMI will have a touch screen to control the air circuit breakers (among other functions). The general feeling (old timers) is that the HMI is the way to go, but we should retain the manual switches (just in case).

What is the general contemporary design trend?

Thank you.

 

[OhioAviator]

My experience has taught me that you should retain the manual open/close/lockout operating switches but also add another switch for 'local/remote' control. You may never need to go to manual control, but it's cheap insurance.

 

[jghrist]

If an emergency arises in the station, it's best to be able to trip the breakers in the manner everyone is already used to - turn the handle on the control switch. Maybe someday the first instincts of operators will be to touch a symbol on a screen, but this day has not arrived.

You could get rid of the lockout feature, but the trip through the manual control switch should remain enabled IMHO.

 

[slavag]

Hi.
Open command to breaker MUST be handle control, directly connected to the trip coil and prefererd with latch option.
Close command-- up to you, for my pinion, today is via HMI.
Best Regards.
Slava

 

[cranky108]

SEL also offers push button controls, but I suggest if you go this way consiter the covers.

 

[DTR2011]

the latching function of the old switches sure does clear up why a 'nuisance trip' isn't the relay or HMI system.

 

[oldfieldguy]

Referring to draw-out switchgear, the old switch on the door of the gear ALWAYS trips, in my opinion, regardless of breaker position (racked in vs. racked out) or the condition of any 'local-remote' switch.

With new relays you can make the operation of the door switch an 'event' for record, but that door switch should be the common denominator short of mechanically tripping a breaker.

old field guy

 

[suhagpatel]

My experience is that the HMI is great as long as it functions properly. At some point in the future it is possible that the TouchScreen or HMI computer will fail. In this scenario the only way for an Operator to open/close CB's is through the front panel of the relay. Most operators are not familiar/comfortable with poking around on the front panel of the relay and will probably call the relay tech for support. Because the potential for HMI falure exists, I would recommend retaining manual trip/close control switches for the sake of the operators.

 

[dpc]

+1 for providing manual trip switch directly connected to breaker trip coil.

 

[slavag]

Hi.
Very imortant,Cranky's : suggest if you go this way consiter the covers

From last friday :-(

 

[etronics]

As long as you have some sort of backup control IE: SCADA the local control switches are not necessary. We've done it at a few of our substations and have had very few problems. Most issues are with operator error. If the SCADA system is the main interface for both systems then that would be a single failure point and would not be truly redundant.

There is nothing wrong with having manual control switches but HMIs have proven themselves to be a reliable technology and are used extensively in other industrial applications. In general the substation world is very conservative and not exactly on the cutting edge of technology.

 

[vndo]

We are manufacturers of paralleling switchgear for standby power application. As a standard we provide an auto/manual switch (A/M) contact and local break control switch in addition to touchscreen control. Manual position of the A/M switch is annunciated on the touch screen. Breaker is controlled from touch screen only when A/M switch is in auto.Failure of touchscreen is rare but a possible event.