TECHIVICA L INFORMATI0 N SERIES 

GENERAL @ ELECTRIC 

The purpose of this report is to review the development of a low cost surge counter and to provide operating 

theory and instructions for their usage. This counter 

was specifically developed for detecting transient overvoltages on 115 volt AC power systems. 

A DIAC-type device provides the threshold function to 

turn on a Silicon controlled switch, discharging an energ 

storage capacitor into the solenoid of an electromechanical counter. 

NO. 64GL166 

DATE 11/1/64 

O.E. CLASS 111 

GOVT. CUSS None 

No. PAGES 11 

AUTHOR 

F. D.Martzlo8f 

Ninety of these have been built for distribution 

among sponsors of the Transient Overvoltage Pooled Progra 

and will be installed in residences across the country. 

The results of this broad base statistical investigation 

will be compiled and serve to give a rough indication of 

the magnitude of the problem to be expected for transient 

sensitive circuits. 

SUMMARY 

SUBJECT 

SURGE RECORDING 

KEY WORDS 

TITLE 

LOW COST SURGE COUNTER 

REPRODUCIBLE tow FILED AT G.E. TECHNICAL DATA CENTER 

BLDG. 5, SCHENECTADY, N. Y. 

I TRANSIENTS, SURGE RECORDER, SURGES, DIAC, SCS 

INFORMATION PREPARED FOR Transient Overvoltaee - Pooled Prosam 

TESTS MADE BY F.D. Martzloff 

AUTHOR F.D. Martzloff 4- fl.-C 

COMPONENT Systems & Circpit? Pro~ram 

APPROVED J.P. Hanna 
1. Introduction 

Transient overvoltages on low voltage circuits have been recorded since 

1962 with automatic recording oscilloscopes, under a program sponsored by a 

number of Departments. 

The most comprehensive data available in this field has been reported 

in TIS 63GL144, listing 30 locations where such recordings were made. 

However, the selection of these locations was rather arbitrary, either 

these were homes or businesses in the Schenectady area where permission to 

install a recorder was obtained, or they were areas where equipment failures 

occurred and were brought to our attention so that a recorded could then be 

installed. In both cases, this selection is far from the statistician's 

ideal. In an attempt to cover a broader base for the locations of the homes 

where recordings should be made, the sponsors of the program agreed to underwrite the development of a low-cost recorder which could be readily installed 

in the homes of the engineers of those departments, and thus provide this 

broader base for a more valid estimate of the transient's frequency of 

occurrence. 

The purpose of this survey could be accomplished if two or three levels 

of surges were investigated, in the range where semiconductor failures are 

most likely to occur. 

It would also be desirable to design the recorders so that they may 

trigger at different levels and operate at other than 115 AC supply voltages. 
OPTIONAL ,-- 

SER\ES I 

I 

RES \STANCE 4 

I 

ONE-SWOT SURGE \ND\CATOR 
2. Initial Approaches 

Some very simple ideas towards meeting the basic requirement of at least 

a one-shot surge recorder included various schemes. For instance, the failure 

of a diode can be used as a calibrated voltage sensor, or turning on the AC 

power by a surge-triggered DIAC-type device into a fuse which would then blow, 

or blowing a fuse by the reverse current in controlled avalanche diode, etc. 

2.1 One-shot diode recorder 

The one-shot diode circuit would only have required two back-to-back 

diodes and a fuse. Tests have shown that the failure of the 1N679, for 

instance, under reverse transient voltage is very consistent, so that 

this failure level could be used as threshold. Following failure of one 

diode, in a first approach the second diode would have failed on excess 

forward current, causing the fuse to blow (see sketch). In a second 

approach, the high forward current in the remaining diode would then 

cause the fuse to blow first. In the second case, examination of which 

diode had failed would indicate the polarity of the surge. In each case, 

a neon lamp across the fuse would have indicated the failure, i.e. the 

occurrence of a surge exceeding the threshold level. Resetting of the 

indicator would then require one or two diodes to be replaced, in addition 

to the fuse. 

The advantage of this is the low initial cost (under $2) offset, 

however, by the replacement costs for each resetting (about 75~). The 

other disadvantage is the need to examine the diode for polarity discrimination, and the limited number of threshold levels existing in available 

diodes. 
2.2 Controlled avalanche diode recorder 

In this circuit, the high current following diode failure would be 

replaced by the avalanche current above the knee of the diode characteristic. 

Again, two diodes would be mounted back-to-back with a fuse in series and 

with a neon lamp in parallel to indicate a blown fuse. 

However, the energy available during avalanche is likely to be small 

and too sensitive a fuse might be required. Furthermore, the leakage 

current in the diode might not be sufficient to fire the indicating neon 

lamp across the blown fuse. 

2.3 DIAC-type recorder 

A slight modification of the controlled avalanche diode appeared 

possible, by using a DIAC-type switch, which would be turned on by a 

surge above the threshold of the device, while the follow-current from 

the AC line would then supply the necessary energy to blow the fuse. 

Resetting would then only require a fuse replacement. 

However, the unavailability of DIACs (or SSS switches) with a high 

threshold required the use of a voltage divider in order to trigger at 

surge voltags above 300 volts, which is the case here. It then became 

difficult to provide a divider with sufficiently high impedance to avoid 

loading the circuit under test and still with low enough impedance to 

provide holding current during the remaining part of the 60 cps half wave 

following the surge. 

Furthermore, it was also found that turn-off of this device occurred 

very fast, so that if the surge was a damped oscillation. the switch 

could be turned on by the first loop, but promptly turned-off as the surge 

oscillated into the next loop of reverse polarity with insufficient 

amplitude to turn it on. Thus, the 60 cps follow current could not occur. 

3 
After reviewing and trying some of these three approaches, it became 

apparent that some latching had to be provided by some form of stored 

energy, with the surge supplying only the trigger pulse. As soon as the 

concession was made, against the initial concept of minimum circuitry, 

to provide stored energy, it seemed that using this stored energy to 

drive a counter would produce more interesting results than just to blow 

a one-shot fuse. This led to the development of the recorder described 

in the following section. 

3. Counter-output Recorder 

The device shown on the opposite page was developed as the result of the 

experimentation and considerations discussed above. It is capable of triggering 

for surges as short as 0.5 ps in excess of the design threshold level, for one 

polarity. The threshold level is determined by the combined parameters of an 

input attenuator and SSSswitch. Reverse polarity is recorded by reversing the 

connection, i.e., the plug in the outlet. 

In contrast with available commercial recorders which generally use a 

coaxial input lead, with attenuators sometimes built in the probe, this 

recorder is connected to the circuit to be measured by a standard appliance 

cord. This provides an easy method of connection, with the added feature that 

the recording takes place at the end of 6 feet of lamp cord, where an appliance 

would normally be connected. Fast surges (less than 0.1 ~ls rise time) would 

obviously be distorted by such a crude connection, but this is not the point 

here where the expected surges will have 0.5 ps rise time or more, as demonstrated 

by a number of oscilloscope recordings. 

The threshold level is stable within 210% of the nominal value for a 

0 temperature variation of 225% C, which is more than what can be found between 

hot attics or cold basements. 
Surge counter - Active circuit and counter . The left side of the circuit, 

shielded by tubing shown in preceding photograph, is visible here. 

(ATL Photo No. 833103) 
Surge counter - connecting cord is only accessible part, with 

non-reset counter behind window. 

Surge counter - cover removed. 

1964-vintaae surae counter mentioned in the "Where do we ao from here?" article 

(See GE TIS Report "Low-Cost Surge Counter" in Part 5 of the Anthology) 
The level of each individual unit has also been set within 10% of nominal 

value by matching the SSS switch with the input divider ratio. 

Two levels were selected for the threshold: 1200 volts, corresponding 

to a value where, for instance, low cost appliance half-wave rectifier circuits 

feeding a capacitor or a battery will begin to fail; the other level is 2000 

volts, where most half-wave rectifier circuits will not survive, and where 

appliances with an input transformer may start failing. Thus, the results of 

the survey will yield statistics at these two levels. 

3.1 Principle of operation 

An incoming positive surge is attenuated in the R~-c~/R~-c~ divider. 

If the voltage across R2-C2 exceeds the turn-on voltage of the DIAC-type 

SSS, this voltage is applied through the divider R3R4C3 to the gate of 

the SCS. Excessive gate current is prevented by this R3R4C3 network, 

while the diode D protects the gate against negative pulses. Cg also 1 

helps to reduce firing of the SCS by spurious noise and attenuates the 

signal leaking through the junction capacitance of the SCS at levels 

below the threshold. 

With the SCS turned on by the gate signal, the capacitor C will 4 

discharge through the coil of the counter which indexes for one count. 

The anode gate resistor R, stabilizes the turn-on of the SCS and prevents 

any possible rate effect. With the 60 cps supply to the rectifier, the 

latter is not very likely; a resistor in the anode circuit would further 

reduce the possibility of rate effect, but was found unnecessary in this 

case. 

The capacitor C4 is charged to a fraction of the line voltage through 

the divider R5-R6 and the diode D2. The diode D2 is a selenium rectifier 
in order to withstand the incoming negative surges which are implicitly 

expected in this application, and which would promptly cause failure of 

an unprotected silicon diode in this half-wave circuit. 

The values of the divider R5-R4 are high in order to reduce the 

follow-current through R5, D2,S and SCS below the holding current of the 

SCS. The gate resistance Rq contributes to making this holding current 

relatively high so that the resistance R5 is held low enough to allow 

recharging the capacitor in a reasonable time. 

The input attenuator is enclosed in a shield in order to eliminate 

the variable stray capacitances which would affect the divider ratio. 

The gate circuit of the SCS and the SCS are enclosed in the same shield 

in order to eliminate noise radiation into the gate circuit. 

3.2 Limitations 

The threshold is obviously fixed for a given unit. It could just 

as obviously have been possible to provide an attenuator with several 

levels and a selector switch. However, it was decided to limit each 

unit to a single level in order to avoid possible confusion in the records 

on the position of the selector, as well as to avoid bringing a metal 

shaft out of the insulating box and out of the attenuator shield. 

The recorder triggers on one polarity only, reducing in half the 

number of random surges likely to be recorded in a given period. On the 

other hand, this allows discrimination, where desirable, of the surge 

polarity. If it is necessary to record both pokrities at the same time, 

two recorders with the plugs reversed (the plugs are marked) can be used. 

The resetting time of the recorder is determined by the charging 

cycle of the energy storage capacitor. We saw why this had to be long. 

However, this is no problem in the case of the erratic surges which are 

expected to be recorded in homes. On the other hand, it is conceivable 

6 
INSTRUCTIONS - Plug in any 110 volt outlet where occurrence of 

surge. 18 to be recorded. Enter date, counter readinp and 

location (city) in appropriate column. Also ahow in remark 

WARNING - Do not remove cover without firat disconnecting cord 

from outlet. For use by General Electric employees only! 

INSTRUCTIONS - Plug in any 110 volt outlet where occurrent. 

of .urges ia to be recorded. Enter date, counter readin' and location (city) in appropriate column. Alao show in remrk colunn if any unusual activity occurred during recording 
that if the recorder were connected to a circuit where surges would occur 

at the rate of several per minute, the SCS would be continuously triggered, 

so that the capacitor would never reach a sufficient charge to actuate 

the counter. 

4. Recording Procedure 

Previous recordings performed with oscilloscope-camera combinations have 

shomthat one~ekis more than sufficient to determine the pattern of household 

switching surge occurrence. On the other hand, surges due to power system 

switching and lightning are quite erratic, but tend to involve all the homes 

in the area. 

Therefore, the following procedure is suggested: a 1200 volt recorder 

should be installed in a selected home, and left for one week. Enter start and 

finish date and counter readings at these dates, and install the recorder in 

the next available home. From previous oscilloscope recordings, we would 

expect about a 70% probability that very few or no surges will be indicated, 

in which case there is no point in installing the 2000 volt recorder. In 

those homes where the 1200 recorder will have indicated surges, the 2000 volt 

recorder should be installed next in order to determine the number of the 

surges in excess of 1200 volts which even exceed 2000 volts. Of aourse, the 

two recorders could be installed simultaneously at the same location, but this 

would require two units. With a split of 3 units at 1200 volts and 1 at 2000 

volts, more of those 70% locations where little surge activity is to be found 

can be covered in a given period of time. 

As soon as the peel-off data sheet secured to the recorder is filled, 

(see opposite page), it should be returned to ATL for compilation of the 

statistics. Spare sheets have been provided with each counter. 

all % watt carbon 

C1 150 pF 500V mica nominal (2000 volts) 

250 pF 500V mica nominal (1200 volts) 

C2 .O1 )IF lOOV mylar 

C3 -001 pF 500V ceramic 

C4 50 pF 50V 

F 4 amp fuse 

SSS Hunt Electronics "logic device" 

SCS 3N85 

Dl IN457 

D2 6RS6PH4RADl 

S Elmeg counter OZ3R10154 

Casing: Lafayette Cat. #19G2001 

Cover: Lafayette Cat. #19G3701 

Total Parts cost (in quantities of 100) $18.00 

Counter only $10.00