803A - No Load to Lugs

Hello All!

I have an 803A with roughly 2000 hours on it. It runs regularly. During use one day, it ceased to send power to the breaker panel it’s hooked up to. After investigation, I saw the green AC Interrupter light was off and would not come back on. The unit is not hooked to anything that can pull more than 75% load, so no way it could have overloaded. My spare 803A is working just fine on the same circuit. I’ve gone through many of the threads on this forum and can’t seem to narrow it down. Short of buying some high dollar parts such as overload relays, I'm hoping I've missed something simple. Here’s the general situation:

No Load at Lugs, AC Circuit interrupter light will not come on when S5 switch turned to CLOSED.

The circuit interrupter light, DS7, has been tested and works correctly. The Circuit Interrupter switch, S5, has been tested and functions correctly. Voltage tested on switch S5 when running indicates 24 volts at S5-2 & S5-3, however S5-5 only shows 2 volts….? My understanding is S5-5 should have 24 volts also. This traces all the way back to TB5-16 I believe and shows 2V there as well.

K1 Relay has been replaced with brand new unit.

K15 Relay replaced with brand new relay.

Hertz Gauge is registering at 60HZ.

Voltage Gauge is indicating 240V.

Convenience receptacle tests with meter to 120V. Confirmed with power tool the convenience receptacle works as intended and the generator is producing power. Just not sending it to the lugs.

Thank you in advance!

Does the contactor close while holding the switch up? I assume no?
Have you tested either the old or new contactor per the TM by applying ground and 24v to the small terminals?
If so what was the result?
If not... test that first to confirm the contactor is functional.
Are you also only getting 2V at the contactor with the switch held up?

Sound like you may not be getting 24 volts to the contactor terminal X when the set is running.
Start the set and check for 24 volts at K20 terminal 6 & 9.
K20 closes when the oil pressure come up. 24 volts come into K20 on terminal 9 and out terminal 6 to provide 24 colts to the X terminal of the K1 coil.
The circuit interrupter switch S5, diode, K1 contracts and K8 provide the path to ground for the other side of K1 to cause it to close.
K1 should close and contactor light should illuminate when S5 is in the up position regardless if K8 "thinks" there is a OL or SC fault.

Ray70 said:

Does the contactor close while holding the switch up? I assume no?
Have you tested either the old or new contactor per the TM by applying ground and 24v to the small terminals?
If so what was the result?
If not... test that first to confirm the contactor is functional.
Are you also only getting 2V at the contactor with the switch held up?

Click to expand...

The contactor does not close while holding the switch.
The contactor has been tested and is functional
the 2V I stated was actually showing up as a negative 2V on my meter....? It remains unchanged when I hold the switch up.

kloppk said:

Sound like you may not be getting 24 volts to the contactor terminal X when the set is running.
Start the set and check for 24 volts at K20 terminal 6 & 9.
K20 closes when the oil pressure come up. 24 volts come into K20 on terminal 9 and out terminal 6 to provide 24 colts to the X terminal of the K1 coil.
The circuit interrupter switch S5, diode, K1 contracts and K8 provide the path to ground for the other side of K1 to cause it to close.
K1 should close and contactor light should illuminate when S5 is in the up position regardless if K8 "thinks" there is a OL or SC fault.

Click to expand...

Started and check for voltage at K20 terminals 6 & 9. Terminal 9 has voltage of 26.7V and terminal 6 is showing -2V. I shut the unit down and swapped out K20 with a brand new relay. Within just a couple seconds of starting the unit back up, CB1 popped and the unit shut itself down. The old relay was reinstalled and CB1 was reset and the generator fires right back up. Again after reinstalling the new relay, CB1 popped again.

Bench test your new relay, IAW the -24 TM. When you say, "new relay", what do you mean? New from a package? New, from your other set? Are you sure its the right relay? It looks, the same, it has the same part number on it? There ARE different relays that sure look the same, but are not.

Guyfang said:

Bench test your new relay, IAW the -24 TM. When you say, "new relay", what do you mean? New from a package? New, from your other set? Are you sure its the right relay? It looks, the same, it has the same part number on it? There ARE different relays that sure look the same, but are not.

Click to expand...

The replacement relays I'm referencing are brand new in sealed packages. Same manufacturer and part numbers. See attached PDF with photo.
Here's where things start to not make sense.....

I tested both the old and new relays IAW TM -24; 2-33.2 (See Attached PDF for photo). For some reason, both old and new relays test as functional and actuate correctly when power is applied to terminals A & B of the relays. As I had mentioned before, I have another 803A right next to the unit in question, so after everything bench testing fine, I went ahead and swapped the K20 relays between the units. My spare 803A has no change and produces power to the lugs no problem. The problem unit again pops the CB1 with the swapped K20 relay. When I swap them back to their original positions, the problem gen doesn't pop the CB1 breaker, but will not still allow S5 to light up. For some reason, the problem Gen will only run with the 'Old' relay in place. My other gens work regardless of which relay I put in the K20 position.

To summarize, I've had 3 separate K20 relays in the problem genset and the only one that won't pop the breaker is the original one, however that original one works fine in other gensets and tests as functional.

Thank you for helping me through this one!

The K5 does not "Allow" the S5 to light up. The S5 is a switch. So I guess you mean DS7, the AC Circuit Breaker light? The DS7 is controlled by the K1. The only way the DS7 can come on is because the K1 turns on. Look at the schmatic. Do not get fixed on DS7. You need to know why K1 wont energize.

So, with a "New" K20 installed in the set, upon start up, without you doing ANYTHING, not switching any thing on, the CB1 pops. Is that right?

Guyfang said:

The K5 does not "Allow" the S5 to light up. The S5 is a switch. So I guess you mean DS7, the AC Circuit Breaker light? The DS7 is controlled by the K1. The only way the DS7 can come on is because the K1 turns on. Look at the schmatic. Do not get fixed on DS7. You need to know why K1 wont energize.

So, with a "New" K20 installed in the set, upon start up, without you doing ANYTHING, not switching any thing on, the CB1 pops. Is that right?

Click to expand...

Sorry for the confusion....Yes you are correct on your assumption. With any 'new' or otherwise functional replacement of K20 relay and without doing anything, the CB1 pops within a few seconds of generator startup. The DS7, AC Circuit Interrupter light does not light up. K1 is not closing. In diagnosing why, I tested the S5 switch function and it passed. However there was a discrepancy in the voltage being provided to that switch. Terminal 5 of switch S5 is showing -2 Volts instead of 24V. We traced this back to terminal 16 of TB5 which is showing the same. This points to Terminal J6-35, which I can't seem to find.
There was a comment above relating the Relay K20 indicating both terminals 9 and 6 should have 24V. Only terminal 9 has 24V (26.5 actually) and can't get it over to terminal 6. When the relay is replaced it always kicks CB1 within a few seconds. Maybe these are separate problems.

Here's a summary of knowns:

- K1 is not getting 24V to terminal X. It's showing -2V. When I hold the S5 switch up, this -2V goes to almost a zero reading. K1 has been replaced with a new in box unit and tested as functional.

- K20 relay is showing 26.5V at terminal 9 and -2V at terminal 6. Any replacement of this K20 with new or other functional relay from another gen-set results in CB1 popping and engine shutdown within a few seconds of startup.

- Switch S5 is not getting 24V power to terminal 5. It's showing -2V. S5 switch has been tested and is functioning correctly.

You wrote:

Sorry for the confusion....Yes you are correct on your assumption. With any 'new' or otherwise functional replacement of K20 relay and without doing anything, the CB1 pops within a few seconds of generator startup. The DS7, AC Circuit Interrupter light does not light up. K1 is not closing. In diagnosing why, I tested the S5 switch function and it passed. However there was a discrepancy in the voltage being provided to that switch. Terminal 5 of switch S5 is showing -2 Volts instead of 24V. We traced this back to terminal 16 of TB5 which is showing the same. This points to Terminal J6-35, which I can't seem to find. (J6 is one of the canon plugs under the control panel. Open the right bottom door and stand on your head. Look up. There should be J6. And P6 is in the control panel, on the bottom. Should be also marked.)
There was a comment above relating the Relay K20 indicating both terminals 9 and 6 should have 24V. Only terminal 9 has 24V (26.5 actually) and can't get it over to terminal 6. When the relay is replaced it always kicks CB1 within a few seconds. Maybe these are separate problems.

Here's a summary of knowns:

- K1 is not getting 24V to terminal X. It's showing -2V. When I hold the S5 switch up, this -2V goes to almost a zero reading. K1 has been replaced with a new in box unit and tested as functional. (If you switch your leads, I bet you get +2 volts. This sounds like a loose connection, or maybe a burnt pin in J6?)

- K20 relay is showing 26.5V at terminal 9 and -2V at terminal 6. Any replacement of this K20 with new or other functional relay from another gen-set results in CB1 popping and engine shutdown within a few seconds of startup.

- Switch S5 is not getting 24V power to terminal 5. It's showing -2V. S5 switch has been tested and is functioning correctly.

Looking at Kurt's description of S5, I'm confused as far as you saying S5 is not getting 24V.
Sounds like the contactor gets +24 to the X connection through K20 and gets its ground from S5, so that makes me assume you should not expect to have 24V power at S5, but rather continuity to chassis... or am I missing something??
Personally my next step would be to send 24V to the X connection on the contactor ( disconnect the original wire first ) from the 2nd battery, starter post or other 24V+ source
Fire us the gen and verify if things work as they should.
If so, go back to tracing down the lack of 24V on K20 pin 6 Measure right at the K20 socket, as Guy stated it definitely sounds like a loose or corroded connection somewhere.

Ray70 said:

Looking at Kurt's description of S5, I'm confused as far as you saying S5 is not getting 24V.
Sounds like the contactor gets +24 to the X connection through K20 and gets its ground from S5, so that makes me assume you should not expect to have 24V power at S5, but rather continuity to chassis... or am I missing something??
Personally my next step would be to send 24V to the X connection on the contactor ( disconnect the original wire first ) from the 2nd battery, starter post or other 24V+ source
Fire us the gen and verify if things work as they should.
If so, go back to tracing down the lack of 24V on K20 pin 6 Measure right at the K20 socket, as Guy stated it definitely sounds like a loose or corroded connection somewhere.

Click to expand...

Thank you for the advice. After disconnecting the original wire, I went ahead and sent 24V directly to terminal 'X' from the starter and the gen is working fine. Switch S5 works as intended and illuminates GS7 light when put to 'Close' and the main lugs are powered. When I disconnect the jumper, we're back to the same problem.

The k20 pin 6 is still lacking 24V. It appears the K20 pin gets it's power from K20 pin 9 once the contacts close. What has to happen for K20 relay to close?
I've pulled and cleaned all the barrel connectors and reinstalled. As it pertains to S5....I did read on this forum somewhere that S5 Terminal 5 should have 24V and when I tested this one my other 803A I did confirm that pin 5 of S5 does in fact have 24V. Not sure if this is pertinent, but it seems something is off.

I'll keep checking for loose connections, but can't come up with one yet.

K20 is the Oil Pressure relay. Normally when the set is running K20 is closed.
Relay K20 closes when you have S1 in START and the Oil Pressure has built up. K20 closes sending 24 Volts to K1. Other contacts in K20 create a "latching" circuit to hold K20 closed so when you release S1 back to Prime/Run K20 remains closed.
If the Fault monitor detects certain faults it will trip relay K12 which drops power to K20 causing it to open.

Just for the hell of it, unplug the fault indicator panel and see how the machine performs.