Murphy Tattletale Annunciators and Magnetic Switches for Engine and Motor Shutdown

Latching trip devices that act on Swichgage and switch signals

The Murphy Tattletale annunciators and magnetic switches translate Swichgage contact operations into decisions and operate the alarm or shutdown device. They are the electrical load-carrying devices for the alarm or shutdown circuit. The difference between the two types is that a Tattletale annunciator shows which monitored function failed, while a magnetic switch does not. Magnetic switches work basically as a latching relay.

They are used with engines or electric motors. On battery-coil ignition engines the switch opens the ignition coil circuit to shut down; on magneto or capacitor discharge ignitions it grounds the ignition output; some models can trip fuel valves as well. Diesel engines are stopped by closing the fuel or air supply, and for electric motors various models operate the motor starter or holding coil directly or with a Murphy transformer-relay assembly.

Technical specifications

The bulletin covers a family of models. The table lists the base models and their descriptions as printed.

How the family is organized

Models are electrically tripped relay-type devices. Versions exist for battery power, 120 VAC, conventional magnetos and capacitor discharge ignitions. Energized-to-run models allow closed-loop circuitry, while others draw momentary power to trip. All models have a weather-resistant case with screw terminals. Manually reset models have a face-mounted reset push button that also serves as the fault indicator on the Tattletale version, so only the unit connected to the failed function pops out.

Electrically reset models perform the same functions and are reset by cycling the supply off and on. Time delay models use solid state timing to lock out contacts for start-up, to allow alarms before shutdown, or to apply power to a shutdown circuit and disconnect it after a set time.

Selecting and protecting a unit

Match the model to the power source and ignition type, the contact action needed (make, break or both), the reset type and the delay. For example, the 760A family is for battery-coil ignition or diesel with start-up lockout, while the MS2120 suits magneto ignition. Option codes cover an auxiliary SPDT switch, an environmentally sealed version and an explosion-proof less case version where applicable, and not every combination is available.

The bulletin warns to always provide proper circuit protection with fuses or circuit breakers, and notes that the 760A cannot be adequately protected by a circuit breaker in a dead short with a battery source, so fuses are the preferred protection. Enovation Controls lists this product family on its Legacy Products page, which describes those items as less popular or outdated but still available for purchase. Confirm current availability and any replacement part before ordering.

How the Murphy Tattletale works

A Swichgage contact opens or closes when a monitored value goes out of limits. The Tattletale or the magnetic switch picks up the signal and latches. It then trips the shutdown device or sounds the alarm.

Where the Tattletale is used

• Diesel engines
• Gasoline engines
• Electric motors
• Generator sets
• Pump drives

Selection checklist for the Tattletale

• Engine or motor type
• Ignition system
• Supply voltage
• Annunciator or switch type
• Time delay need
• Reset method
• Contact arrangement
• Vibration level

Installation, commissioning and maintenance notes for the Tattletale

Mount the unit in a dry place and wire the Swichgage contacts to it. Connect the shutdown circuit and test the trip by opening a contact. Check the wiring and the reset action at regular intervals.

Requesting a quotation for the Murphy Tattletale

Please send the engine or motor type, the voltage and the model needed. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Tattletale device type

It is a latching annunciator or magnetic switch.

Tattletale maker

It is made by Murphy.

Tattletale role

It carries the load for the alarm or shutdown circuit.

Tattletale input

It acts on Swichgage and switch signals.

Tattletale annunciator

The annunciator shows which monitored function failed.

Tattletale magnetic switch

The magnetic switch does not show the failed function.

Tattletale latching

A magnetic switch works like a latching relay.

Tattletale coil ignition

On battery-coil ignition the switch opens the ignition coil circuit.

Tattletale magneto ignition

On magneto ignition the switch grounds the ignition output.

Tattletale fuel valves

Some models can trip fuel valves.

Tattletale diesel engines

Diesel engines are stopped by closing the fuel or air supply.

Tattletale electric motors

Some models operate the motor starter or holding coil.

Tattletale model 117

The 117 shuts down 12 to 32 V battery-coil ignition or diesel engines.

Tattletale model MS2100

The MS2100 operates from 120 VAC or capacitor discharge ignition.

Tattletale model MS2110

The MS2110 operates from 12 or 24 VDC or 24 VAC.

Tattletale model MS2120

The MS2120 operates from magneto ignition.

Tattletale dry contacts

The MS2100 series has dry contacts that make two circuits and break another.

Tattletale model 518PH

The 518PH wires the Swichgage contacts in a closed loop.

Tattletale vibration model

The 518E is for high vibration and runs on 12 V only.

Tattletale model 520APH

The 520APH has a 30 second delay on one Swichgage input.

Tattletale delay range

Delays from 5 to 120 seconds are available.

Tattletale model 521PH

The 521PH grounds a magneto or capacitor discharge ignition.

Tattletale lockout

The 760A series gives a time delay lockout at start-up.

Tattletale lockout times

Delays are 15, 30 or 60 seconds.

Tattletale reset

The 760A resets automatically and the 761APH has a manual reset.

Trip records for the Tattletale

Record the trip cause, the reset time and the date of each event.

Choosing the right Tattletale model

Choose the model from the ignition type and the supply voltage.

Documents and quotation

The attached bulletin 78793 (revision 2014/09/27) is the source for the table. Seven Star LLC supplies Murphy products as an independent supplier in Muscat. Send the exact model, voltage, delay time and options with your enquiry. Browse controllers and data acquisition for related products.