CHAPTER 5: SETTINGS CONTROL ELEMENTSN60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL 5-2055Example 1: Breaker trip circuit integrity monitoringIn many applications it is desired to monitor the breaker trip circuit integrity so that problems can be detected before a tripoperation is required. The circuit is considered to be healthy when the voltage monitor connected across the trip outputcontact detects a low level of current, well below the operating current of the breaker trip coil. If the circuit presents a highresistance, the trickle current falls below the monitor threshold, and an alarm is declared.In most breaker control circuits, the trip coil is connected in series with a breaker auxiliary contact that is open when thebreaker is open (see figure). To prevent unwanted alarms in this situation, the trip circuit monitoring logic must include thebreaker position.Figure 5-102: Trip circuit example 1Assume the output contact H1 is a trip contact. Using the contact output settings, this output is given an ID name; forexample, “Cont Op 1." Assume a 52a breaker auxiliary contact is connected to contact input H7a to monitor breaker status.Using the contact input settings, this input is given an ID name, for example, “Cont Ip 1," and is set “On” when the breaker isclosed. The settings to use digital element 1 to monitor the breaker trip circuit are indicated (EnerVista example shown).Trip coil52aUR-series devicewith form-A contactsI = current monitorV = voltage monitorDC–827073A2.CDRH1aH1bH1cIV DC+
