The functional diagrams describe the relay’s protection functionality in detail and picture the default connections.
The motor differential protection MPDIF1 is used to detect motor internal winding faults. The OPERATE output is connected to the Master Trip and also connected to signal output X110-SO4 via generic timer TPGAPC3 .The OPR_LS output is connected to alarm LED 1 and the OPR_HS output is connected to alarm LED 2.
Seven overcurrent stages in total are offered for overcurrent and short-circuit protection. Three stages are for directional functionality DPHxPDOC, while the others are only for non-directional overcurrent protection PHxPTOC.
PHLPTOC1 can be used for overcurrent protection, and PHIPTOC1 for the short-circuit protection. The operation of PHIPTOC1 is not blocked as default by any functionality and it should be set over the motor start current level to avoid unnecessary operation.
The motor load jam protection JAMPTOC1 is used for protecting the motor in stall or mechanical jam situations during the running state. The motor jam protection function JAMPTOC1 is blocked by the motor start-up protection function.
The OPERATE outputs are connected to the Master Trip. The OPERATE outputs are also connected to the alarm LED 4, except for PHIPTOC1, which is connected to the alarm LED 3. LED 3 is used for short-circuit protection alarm indication; LED 4 is used for combined protection alarm indication, including overcurrent protection, earth-fault protection, phase unbalance protection, voltage protection, motor jam protection, loss of load protection and frequency protection.
Three stage non-directional earth-fault protection EFxPTOC is offered to detect phase-to-earth faults that may be a result of, for example, insulation ageing. In addition, there are two directional protection stages DEFxPDEF which can also be used as non-directional earth-fault protection without residual voltage requirement. However, the residual voltage can help to detect earth faults at a low fault current level selectively and to discriminate the apparent residual current caused, for example, by partial current transformer saturation at motor start-up.
The earth-fault protection is blocked when the short-circuit protection PHIPTOC1 is started. The OPERATE outputs of the earth-fault protection functions are connected to the Master Trip and alarm LED 4.
Three instances of overvoltage protection PHPTOV1…3 and undervoltage protection PHPTUV1…3 offer protection against abnormal phase voltage conditions. The three-phase undervoltage protection is blocked during motor start-up to prevent unwanted operation, in case there is a short voltage drop. Also if the fuse failure is detected, the undervoltage function is blocked.
The OPERATE outputs of voltage functions are connected to the Master Trip and alarm LED 4.
The positive-sequence undervoltage PSPTUV1/2 and negative-sequence overvoltage NSPTOV1/2 protections are included to protect the machine against single-phasing, excessive unbalance between phases and abnormal phase order. The positive-sequence undervoltage and negative-sequence overvoltage functions are blocked during motor start-up to prevent unwanted operation, in case there is a short voltage drop. Also the binary input X105-BI1, which indicates the motor rotation direction, is used to block these functions by default.
The OPERATE outputs of voltage-sequence functions are connected to the Master Trip and alarm LED 4.
The residual overvoltage protection ROVPTOV1...3 provides earth-fault protection by detecting an abnormal level of residual voltage. It can be used, for example, as a non-selective backup protection for the selective directional earth-fault functionality. The OPERATE outputs are connected to the Master Trip and alarm LED 4.
The single-phase overvoltage protection PHAPTOV1 and single-phase undervoltage protection PHAPTUV1 are used for voltage protection by using the same extra single voltage input for terminal of the motor. These functions are not connected to disturbance recorder and not configured to trip the circuit breaker by default.
The emergency start function ESMGAPC1 allows motor start-ups, although the calculated thermal level or cumulative start-up time counter is blocking the restart. The emergency start is enabled for ten minutes after the selected binary input X105- BI2 is energized. On the rising edge of the emergency start signal, various events occur.
- The calculated thermal level in MPTTR1 is set slightly below the restart inhibit level to allow at least one motor start-up
- The value of the cumulative start-up time counter STTPMSU1 is set slightly below the set restart inhibit value to allow at least one motor start-up
- Set start value of the MAPGAPC1 function is increased (or decreased) depending on the Start value Add setting
- Alarm LED 10 is activated
A new emergency start cannot be made until the emergency start signal has been reset and the emergency start time of ten minutes has expired.
The thermal overload protection function MPTTR1 detects short- and long term overloads under varying load conditions. When the emergency start request is issued for the emergency start function, it activates the corresponding input of the thermal overload function. When the thermal overload function has issued a restart blocking, which inhibits the closing of the breaker when the machine is overloaded, the emergency start request removes this blocking and enables the restarting of the motor. The OPERATE output of MPTTR1 is connected to alarm LED 5, which is used for thermal overload protection alarm indication. The ALARM output of MPTTR1 is connected to output X115-SO3 via generic timer TPGAPC2.
The restart inhibit is activated for a set period when a circuit breaker is opened. This is called remanence voltage protection, where the motor has damping remanence voltage after circuit breaker opening. Reclosing after a too short period of time can lead to stress for the machine and other apparatuses. The remanence voltage protection waiting time can be set to a timer function TPSGAPC1. The alarm LED 6 is used for restart inhibit alarm indication.
The restart inhibit is also activated when one of the conditions is met.
- An active trip command
- Motor start-up supervision has issued lockout
- Motor unbalance function has issued restart blocking
- An external restart inhibit is activated by one push button through SPCGAPC1_O12 or by a binary input X105-BI3 via MVGAPC1
With the motor start-up supervision function STTPMSU1, the starting of the motor is supervised by monitoring three-phase currents or the status of the energizing circuit breaker of the motor.
When the emergency start request is activated by ESMGAPC1 and STTPMSU1 is in lockout state, the lockout LOCK_START is deactivated and emergency start is available. The MOT_START output of STTPMSU1 is connected to output X115-SO1 via generic timer TPGAPC2.
The motor running time counter MDSOPT1 provides history data since last commissioning. The counter counts the total number of motor running hours and is incremented when the energizing circuit breaker is closed. The alarm of the runtime counter is connected to alarm LED 9. LED 9 is used for general supervision of trip circuit, current measurement circuit, voltage measurement circuit and motor operation time.
Two negative-sequence overcurrent stages MNSPTOC1 and MNSPTOC2 are offered for phase unbalance protection. These functions are used to protect the motor against phase unbalance caused by, for example, a broken conductor. Phase unbalance in network feeding of the motor causes overheating of the motor.
The phase reversal protection PREVPTOC1 is based on the calculated negative phase-sequence current. It detects too high NPS current values during motor start-up, caused by incorrectly connected phases, which in turn causes the motor to rotate in the opposite direction.
The negative-sequence protection and phase reversal protection are blocked if the current circuit supervision detects failure in the current measuring circuit. The binary input X105-BI1, which indicates the motor rotation direction, is also used to block these functions by default.
Two stages LOFLPTUC1 and LOFLPTUC2 are offered for loss of load situation protection. The loss of load situation can happen, for example, if there is damaged pump or a broken conveyor.
The OPERATE outputs of above protections are connected to the Master Trip and alarm LED 4.
Six underfrequency or overfrequency protection FRPFRQ1…6 stages are offered to prevent damage to network components under unwanted frequency conditions. The function contains a selectable rate of change of the frequency (gradient) protection to detect an increase or decrease in the fast power system frequency at an early stage. This can be used as an early indication of a disturbance in the system.
The OPERATE outputs are connected to the Master Trip and alarm LED 4.
The breaker failure protection CCBRBRF1 is initiated via the START input by a number of different protection stages in the relay. The breaker failure protection function offers different operating modes associated with the circuit breaker position and the measured phase and residual currents.
The breaker failure protection has two operating outputs: TRRET and TRBU. The TRRET output is used for retripping its own breaker through the Master Trip 1. The TRBU output is used to give a backup trip to the breaker feeding upstream. For this purpose, the TRBU output signal is connected to power output X100-PO2 and alarm LED 7. LED 7 is used for backup TRBU operate indication.
RTD/mA monitoring functionality provides several temperature measurements for motor protection. Temperature of the motor windings U, V and W are measured with inputs X110-RTD1, X110-RTD2 and X110-RTD3. Measured values are connected from function X110 (RTD) to function MAX3. Maximum temperature value is then connected to the multipurpose analog protection block MAPGAPC1.
Motor cooling air temperature and motor bearing temperature can be measured with inputs X110-RTD4 and X110-RTD5. The protection functionality from these temperatures are provided by MAPGAPC2 and MAPGAPC3 functions.
Motor ambient temperature can be measured with input X110-RTD6 and it is connected to the thermal overload protection function MPTTR1.
The OPERATE outputs are connected to the Master Trip and alarm LED 4.
Arc protection ARCSARC1...3 is included as optional function.
The arc protection offers individual function blocks for three arc sensors that can be connected to the relay. Each arc protection function block has two different operation modes, with or without phase and residual current check. The OPERATE outputs from the arc protection function blocks are connected to the Master Trip and alarm LED 11.