Generator and ATS Transfer Panel Faults

An ATS has two power contactors. One is the mains and one is the generator. A mechanical interlock will not let both levers pull in together. An electrical interlock uses one auxiliary contact to cut the other coil. Either can fail. If the mechanical tongue wears, the coils stay pulled in and the two sources meet on the bar. In that case the panel cover is not forced and the generator is not started by hand. First the control fuse of both coils is switched off. Then the contactors are confirmed open by reading the tails with a clamp under no load. A Schneider or Siemens contactor is chosen to the nameplate current. A small auxiliary relay is not put in place of the large contactor.

Control voltage is 230 V in most panels and 24 V in some. If the control transformer or the 24 V supply is dead, the generator looks as if it runs but it does not take the load. That is not an engine fault. The transformer output is read unloaded and loaded. If it is zero volts, the transformer or its fuse is written and the starter battery is not blamed. If 24 V is present and the contactor does not pull in, the coil resistance and the interlock contact are measured. The supply follows the label of the Mean Well, SITOP or the transformer already in the panel. The wrong voltage burns the coil. No part is fitted before the label is read.

The run between the generator and the ATS is NYY. NYM does not go on that route. The section is written from the generator breaker's rated current and the length of the run. A thin run heats when it takes the load and carbonises the contactor tail. The end is cut back to clean copper. A ferrule is fitted. A twist is not closed with cloth tape. The gland sits in the steel box. An entry without a gland carries oil and dust onto the bar. A small single-phase generator is not left feeding one phase of a three-phase building board. That connection leaves the other two phases empty and swells the neutral.

After the mains returns, the phase order may have changed. The hydrophore and the lift motor run backwards. The sockets look normal. The three phases are read at the contactor output with a clamp and a phase-rotation meter. Reverse rotation is corrected by swapping two tails on the customer panel. A sealed meter is not opened. The lift car is not entered. The thermal amp rating is not increased because a motor is running backwards. The detail is on the lift and hydrophore panel page. If the mains is still absent and the street is dark, the record is AYEDAŞ or BEDAŞ on 186. This page does not replace that record.

If the starter does not crank, the battery voltage and the starter fuse are read first. If the battery is under 12 V and the fuse is sound, the job has left the electrical panel. Oil, fuel, the starter motor and the automatic charger are not stripped on this page. If the generator runs and the frequency does not settle, the regulator and the actuator belong to the generator side. The electrician does not enter that board's parameters. If frequency and voltage are not stable at the ATS intake, the load is not connected. If they are stable and the contactor still does not pull in, the fault is back in the control circuit. The two jobs are not written on the same invoice.

The test is under load and kept short. The mains contactor is opened on purpose, the generator contactor is watched closing alone, then the mains is returned and the generator contactor is seen to open. If there is a moment when both are closed, the test stops. The whole building load is not put on the generator. The lift and the hydrophore are not started before the phase order is confirmed. The test time is written with the building manager. No drill is used at night. No time promise is given.

A measured survey is 750–1,500 TRY. A single contactor, a control fuse or a 24 V supply is written near the breaker band: 1,250–3,200 TRY. If the transfer-panel rail, both contactors, the interlock and the NYY tails are renewed together, the job enters the board band: 6,500–16,000 TRY. Where it falls in that band is not said before the kW label and the run length are seen. The generator engine, the battery and the fuel sit outside this list. The band is an estimate. Materials are invoiced separately. The binding figure is written on site after the measurement sheet is full and before the cover is closed. Workmanship is one year. The phone does not lock the band.

The trial is done with the building manager at the door. The time is chosen so the night quiet is not broken. Even without a drill, the contactor is heard on the stairs. First the lighting and one socket breaker are put on the generator. The lift, the hydrophore and every flat are not loaded on the first step. The generator breaker label must stay above this small load. If the label says 20 kVA and the building sum exceeds it, the load is cut by a list and the breaker is not upsized. The list is signed with the manager: which riser is open and which is closed. If there is no signature, the trial is not started.

When the trial ends, it is written once more that the mains contactor closed alone and the generator contactor opened. If a line says both were closed, the panel is left dead and the building is not put on the generator before the part is changed. The fuel cap is not opened before the generator has cooled. That cap belongs to the generator mechanic. The electrician only closes the ATS cover, after the measurement and with the control fuse down. A copy of the sheet stays with the manager. The next duty technician does not produce the same trial from the start. No time promise is written on that sheet.

A single-phase generator is not clamped onto one phase of a three-phase panel. That job swells the neutral and moves the voltage in the other flats. On a three-phase generator the neutral is not joined to the mains neutral at random. Where the neutral may be bridged is written on the ATS diagram. If there is no diagram, no bridge is made and the maker's diagram is asked for. A diagram is not invented. The earth bar is separate. The generator body is not bridged to a water pipe. The green-yellow conductor lands on the bar with its own screw. If these three lines are empty on the sheet, the trial is not valid.

Before the panel cover is closed, the labels are checked. The mains contactor, the generator contactor and the control fuse are written so they cannot be mixed. An unlabelled coil is how the next duty closes both sources at once. This label sits inside the labour band. It is not a separate decoration line.

The generator taking the load depends on three times before the contactor closes. The first is the mains-fail delay. A blink on the street must not start the generator. On a ComAp, Datakom or Deep Sea label this time is one to five seconds in most buildings. If it has been pulled to zero, every blink cranks the starter and the mechanical interlock wears. The second is the generator's accept window. The contactor does not close before voltage and frequency enter that window. The label usually writes 210 to 250 volts and 48 to 52 hertz. If the label writes something else, the label stands. This page does not invent a window. The third is the mains-return delay. When the mains comes back it is not taken at once. It is waited for while it sits steady. In most panels that is thirty seconds to one minute. If it has been set to zero, the contactors walk back and forth as the mains moves and the two sources meet on the same bar for a moment. The trial is not started before the three times are written. Engine speed and the fuel actuator are not parameters on this board that are open to the electrician.

After the times are written, the accept window is measured on its own. At the ATS intake, frequency and voltage are read with a clamp and a frequency meter while the generator runs with no load. If they sit outside the window, the contactor staying closed is written as a fault and the load is not connected. If they sit inside the window and the contactor still does not pull in, the fault is not in the engine and the work returns to the control circuit. That separation takes the starter battery and the oil cap off the same invoice. If the value on the controller cover has been wiped, a number is not invented. Until the times can be read, the trial is kept short, on the lighting breaker only, with the manager at the door. The lift and the hydrophore are not put on this short trial. Nights and public holidays are a separate rate, and the difference is said before leaving.

The supply of the contactor coil is written on its own. In most panels the coil is fed from the control fuse on the generator side, because once the mains contactor opens there is no voltage left on the building side. If the coil tails are landed on the mains side, the contactor does not pull in even when the generator voltage has settled. That is not a burnt coil. The tails are moved to the fuse on the generator side and the body is not changed. If the coil is 24 V, the supply has to be a battery or a SITOP output that stays up while the generator is running. An adapter that dies with the mains leaves the generator with no load. If the place of the tails is empty on the sheet, the trial is not started.

If the ATS is three-pole, the neutral is continuous and both sources share that conductor. If it is four-pole, the neutral is switched with the contactor too. If the generator alternator has its own neutral-to-earth screw and the mains side also has a bond, a three-pole body keeps both bonds alive at once. Load current returns on the earth wire. The flat's 30 mA trips as soon as the generator takes over, with no faulty appliance. That line is not closed as a leakage fault. The sheet carries the pole count, where the screw on the alternator sits, and two voltages. Neutral-to-earth voltage is read first on the mains and again while the generator is loaded. A few volts on the mains and tens of volts on the generator means the second bond is there. A new bond is not added inside the ATS. The alternator cover belongs to the generator mechanic. The electrician does not open that cover on the excuse of oil. The reading is written, the trial stops, and the two jobs do not enter the same invoice. On a four-pole body the neutral contact is clamped on its own. If the neutral current is clearly larger than the sum of the three phases, the neutral is thin. The section is increased. It is not hidden by changing the pole count. The neutral conductor is not painted green-yellow. Green-yellow is only the body earth.

The clamp is written ten seconds after the lighting breaker is put on the generator. The jump at the moment of closing is the start of the LED drivers and it is not a reason to increase the section. The number after ten seconds must stay under the generator breaker label. If it is above the label, load is cut by the list and the breaker is not upsized. If current shows on a breaker the manager wrote as closed, that breaker is mislabelled or there is a bridge under the panel. The trial stops there. The lift breaker is not opened before that current is explained. The work does not leave Istanbul. Gebze is not written from this page.

The band below is the published 2026 list. It is an estimate. The binding figure is written on site after measurement, and the work starts after that.

Service covers the neighborhoods of Istanbul's 39 districts. Not the whole of Turkey. A survey is not a binding quote.