gti-90 Posted November 20, 2012 Share Posted November 20, 2012 hi, need some advice on the compressor i have. its a ERP 110 litre single stage two cylinder model. when turning on to fill from empty (same when topping up) it runs for roughly 15 secs then the restart switch cuts in, leave it for 30 secs press the switch and it runs for again for 15 secs and so on, the more pressure the quicker it cuts out. it just takes a long time to fill up and when using hungry tools takes a age. any ideas? thanks jack. Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted November 21, 2012 Share Posted November 21, 2012 Does it have oil? Maybe its gone dry? With the drain bung out can you turn the pump easily? If so with the drain bung out will the motor run ok? Maybe the motor is on its way? Quote Link to comment Share on other sites More sharing options...
gti-90 Posted November 21, 2012 Author Share Posted November 21, 2012 Hi, it has oil, motor seems to run ok. I was thinking it is more of a electrical fault?.. But I could be very wrong. Thanks Quote Link to comment Share on other sites More sharing options...
zardos Posted November 21, 2012 Share Posted November 21, 2012 I think they have a thermal cut out, so the motor might be getting too hot (higher pressure means more load and more heat) What does the temp of the motor / piston housing feel like when it cuts out? It probably also has a electrical load cut out and this might be triggering (higher pressure means more load and more power needed) Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted November 21, 2012 Share Posted November 21, 2012 Is the electrical supply good? Has it been running fine upto now? Quote Link to comment Share on other sites More sharing options...
gti-90 Posted November 21, 2012 Author Share Posted November 21, 2012 hi, Zardos, the motor and piston do get quite hot, this is possibly why the thermal cut out switch triggers?.. Cynic-al, the electric supply is good, brand new workshop with all the neccessaries, though there is three flurocent strip lights and when the compressor is turned on they dim a little?.. the problem has been getting steadily worse over roughly four months. before it would only cutout maybe twice to fill the tank from empty, now 20 times. thanks for the replies jack. Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted November 22, 2012 Share Posted November 22, 2012 If the lights are dimming I would say theres either a problem with the supply or its working a lot harder than it used to for some reason. What size is the motor and what supply is the compressor on and the workshop on? I had a friend with the same problem who tried all sorts, in the end he found it would only run near the house, the supply wasn't good enough to his workshop. If they are getting hotter than they used to this would suggest working harder than it used to. If its free running then I guess nothing is ceased or wearing out? No play in anything? The oil is clean and topped up? Does the belt slip at all? Has it got any moisture in it? Does it have an air filter on the inlet and if so is it clean? Does the pressure switch decompress the pump before it tries to start? Are there any leaks that would cause it to run for longer? Is the pressure switch kicking out at the right pressure? I assume it has a safety pressure valve? Maybe one of the safety trips is faulty? Although if its getting very hot then tripping that would show its working. Apart from that I don't know Quote Link to comment Share on other sites More sharing options...
gti-90 Posted November 22, 2012 Author Share Posted November 22, 2012 hi thanks for the reply, - the motor is free enough to turn easily by hand, - the belt doesnt slip. - there doesnt seem to be any play. - the oil is showing 3/4 full on the clear lens bottom of piston housing, its not clear but not defo not black either. - when i undo the drain tap at the bottom of the tank, and the moisture trap on the outlet (filter - regulator) there is moisture present...? - the air filter ontop of the filter housing is present but not looking brand new! .. - the pressure switch is working as i think it should.. when turning on, pressure is leaking from the switch for ten or so seconds then it kicks in and fills up. - safety pressure valve is working. - i think it is tripping out. - i turned it on again this eve, from empty it went to 50 psi then stopped, not very hot, then to 65 and stopped, getting hotter then to 75 hotter again and by the time it was at 100 it was just a bit to hot to keep your hand on,, but only at the top of the cylinder housing everything else was cold (motor - side of piston housing) ?,... i will try to upload the model from the website later. thanks jack. Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted November 23, 2012 Share Posted November 23, 2012 What is it actually tripping? Is there something you have to reset? Quote Link to comment Share on other sites More sharing options...
gti-90 Posted November 23, 2012 Author Share Posted November 23, 2012 hi, its the one at the top of this page. what i have to keep resseting is the blue oval box ontop of the motor, it sais "circuit breaker". but why does it keep resetting? thanks Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted November 23, 2012 Share Posted November 23, 2012 That will trip because either the motor is pulling too much current through working too hard or becuase it has an internal fault or because it is faulty and its tripping at too low current. Do you have any way of testing the current it's pulling? This type of thing http://www.ebay.co.uk/itm/1000-AMPS-DIGITAL-CLAMP-METER-MULTI-TESTER-CURRENT-CASE-/271015620038?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3f19ca2dc6 If you know the hp or kw of the motor or what the circuit breaker is designed to trip at you should be able to get a rough idea of what is normal then monitor it as the pressure builds. If the current is exceeding what you expect then you know there is a fault with the motor / pump, if it seems pretty normal it could be the circuit breaker itself. If you have one of those meters monitor the voltage as the pressure builds too. I know you say all is good but if its a new building theres still a risk that somethings not right. A high load could be causing voltage drop. Read this extract from this website http://ecmweb.com/design/highs-and-lows-motor-voltage Effects of low voltage. When you subject a motor to voltages below the nameplate rating, some of the motor's characteristics will change slightly and others will change dramatically. To drive a fixed mechanical load connected to the shaft, a motor must draw a fixed amount of power from the line. The amount of power the motor draws has a rough correlation to the voltage 2current (amps). Thus, when voltage gets low, the current must increase to provide the same amount of power. An increase in current is a danger to the motor only if that current exceeds the motor's nameplate current rating. When amps go above the nameplate rating, heat begins to build up in the motor. Without a timely correction, this heat will damage the motor. The more heat and the longer the exposure to it, the more damage to the motor. Quote Link to comment Share on other sites More sharing options...
gti-90 Posted November 23, 2012 Author Share Posted November 23, 2012 hi cynic-al, thankyou for taking the time to reply. i dont have one of those multi meters, i have been thinking of buying one for a while so will now get this one as suggested from the bay. when i have it i will then do as you suggested above. it is a long way to the workshop and perhaps low voltage is causing it to trip but the motor isnt getting hot so that would suggest it isnt that problem. cheers jack. Quote Link to comment Share on other sites More sharing options...
gti-90 Posted December 9, 2012 Author Share Posted December 9, 2012 hello, back again.. i have monitored the current from empty to full. the motor nameplate suggests 2.2kw is the working voltage. the clamp meters reading is about 2.2kw or just below untill 60psi, above 60 psi when most pressure is starting to build up it wanders from 1.3 to 2.4 kw its not easy to take a reading from the cable. the motor doesnt get hot atall, not even slightly, but the top of the piston housing does. any ideas? thanks. Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted December 9, 2012 Share Posted December 9, 2012 Have you monitored the voltage as it fills to check the supply is good? Circuit breakers monitor current in amps, P(watts) = V(volts) * I(amps) so if the wattage is staying constant and the voltage is dropping the current has to increase to keep that equation true. If the watts and volts are staying the same I would try swap the circuit breaker. It will get hot as its working, but it depends how hot, if it's a first fill you should be able to leave your hand on it comfortably. Are the veins clear & cooling fan working (if it has one). Is their any moisture in the intake or tank (less compressable so harder to work). Is their any air leaking from the compressor (for example is the decompression sticking on the switch?) making it work longer than would be normal. Is the none return valve sticking between the pump and tank leaving full pressure on the piston all the time? If its none of these I'm stumped! Quote Link to comment Share on other sites More sharing options...
cackshifter Posted December 20, 2012 Share Posted December 20, 2012 If you have a starter switch then maybe the overcurrent trip in there is tripping. What happens if you open a valve in the tank and just let the air pressure go to atmosphere,ie so it fdoesn't build pressure? If it runs continuously Ok like that it's something that is affected by the pressure it has to work against. (you could aslo try removing the belt and trying the motor on its own). OTOH, I suspect it might be something affected by heat eg if it's a single phase capacitor start/run motor (which it very probably is), if the run capacitor is breaking down with heat it might cause the overcurrent trip to drop out, irrespective of air pressure. Then when it all cools it can restart. It's normal for the pump to get hot when working - that happens when air is being compressed. Quote Link to comment Share on other sites More sharing options...
gti-90 Posted December 22, 2012 Author Share Posted December 22, 2012 hi, if i leave the valve open the compressor keeps running, if i close the valve the pressure switch closes, the pressure builds abit then the thermal cutout cuts out. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted December 29, 2012 Share Posted December 29, 2012 Sounds like something is wilting under load then, ie above 60 psi. The 2.2kW on the nameplate is the rated output, about 3hp in English units. So when you say the current is 2.2kW I'm not quite sure what you mean. I'd suggest if possible to take the motor to a rewinders and ask them to check it out. Some places can load up the motors. Or contact ERP in Hull, as I have heard they are one of the more reputable/helpful compressor firms. I know it seems obvious but are you sure the motor fan is working, ie not spinning on the shaft, and airflow not blocked btw? Quote Link to comment Share on other sites More sharing options...
Christophers1247 Posted December 31, 2012 Share Posted December 31, 2012 have you checked inside the pressure switch for burnt contacts. as the pressure builds the motor will work a bit harder so if you have burnt contacts it will cause an overload due to the bad connection. either that or the capacitor inside the case ontop of the motor is faulty. Quote Link to comment Share on other sites More sharing options...
gti-90 Posted December 31, 2012 Author Share Posted December 31, 2012 hi, thanks for the replies. cackshifter - i was a bit confused ignore my 2.2kw reading totaly wrong!. the motor fan is working well. the motor doesnt get slightly hot. airflow seems at it should be. i have checked the voltage as Cynic-al suggested, between the pressure switch and motor no load and under load the same it read a steady 222 volts, as soon as the thermal cutout trips it reads 234-5 volts. christophers1247 - ive had a brief look inside the pressure switch, nothing apparent, but will have a more detailed look tomorrow, thanks for the replies jack. Quote Link to comment Share on other sites More sharing options...
gti-90 Posted December 31, 2012 Author Share Posted December 31, 2012 hi, thanks for the replies. cackshifter - i was a bit confused ignore my 2.2kw reading totaly wrong!. the motor fan is working well. the motor doesnt get slightly hot. airflow seems at it should be. i have checked the voltage as Cynic-al suggested, between the pressure switch and motor no load and under load the same it read a steady 222 volts, as soon as the thermal cutout trips it reads 234-5 volts. christophers1247 - ive had a brief look inside the pressure switch, nothing apparent, but will have a more detailed look tomorrow, thanks for the replies jack. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted January 1, 2013 Share Posted January 1, 2013 You need to check the voltage when it is running on the supply side of the pressure switch. If it is 234-5 volts- lovely, no supply problem , but it points to a duff pressure switch, probably contacts worn out, as you'd be losing those volts in the switch (which must therefore be getting warm).OTOH if it reads 222 you do have some supply issues - that is a big voltage drop. If you DO find a pressure switch issue be aware some have an unloader system that de-pressuries the line between pump and tank, so there is a kind of mechanical soft start - the pump starts up unloaded always. Not all pressure switches have that, so you'd need to get the right one. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted January 1, 2013 Share Posted January 1, 2013 You need to check the voltage when it is running on the supply side of the pressure switch. If it is 234-5 volts- lovely, no supply problem , but it points to a duff pressure switch, probably contacts worn out, as you'd be losing those volts in the switch (which must therefore be getting warm).OTOH if it reads 222 you do have some supply issues - that is a big voltage drop. If you DO find a pressure switch issue be aware some have an unloader system that de-pressuries the line between pump and tank, so there is a kind of mechanical soft start - the pump starts up unloaded always. Not all pressure switches have that, so you'd need to get the right one. Quote Link to comment Share on other sites More sharing options...
gti-90 Posted January 1, 2013 Author Share Posted January 1, 2013 it reads 222 volts the supply side aswell. the contacts inside the switch were slightly blacked so cleaned them up a bit. no difference. im sure the pressure switch does have a "unloader system". thanks Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted January 1, 2013 Share Posted January 1, 2013 you can tell if you have a decompression switch if it has two air connections going to it. Is it a circuit breaker or thermal trip thats cutting out, I though it was a circuit breaker? Did you measure the current (in amps) when running to see if it was getting up to the point where the circuit breaker should trip to check its not a duff circuit breaker thats tripping at too low a current? Good luck Quote Link to comment Share on other sites More sharing options...
gti-90 Posted January 11, 2013 Author Share Posted January 11, 2013 hi, i keep getting set back with this with work but will try to have a good look this weeknd. it reads on the front of the "breaker box" `circuit breaker`, and on the top `thermal reset` .... the switch has a pipe running back to the non return valve and is connected straight ontop of the tank so im guessing its a decompression switch. cheers Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.