This is actually an ACA Allertor

That fact is true. The Allertor had the option to have a Penetrator horn instead of the famous "Toilet" horn.

RESUME

The Penetrator is a series of rotational electromechanical sirens that was produced by Alerting Communicators of America that mainly consisted of 4 models: The P-10, P-15, PN-20, and the P-50. The Penetrator series proved to be one of ACA's most popular sirens throughout the 1980s for their reliability and output, and many can still be found in service today.

MODELS

P-10

The Penetrator-10 (also named the P-10) was the first model to appear in 1980 and was designed as the successor of the Allertor 125 to perfect the design faults the Allertor had, such as ice buildup in the projector drum. It took the horn and intake cone from the ACA Howler and enlarged and redesigned them to fit the Allertor's proportions and would be sold alongside the Howler. It uses a dual-sided Doerr (later Baldor) 10 hp AC motor to drive both the 18-inch chopper and the rotator at once and was available in 8-port single tone and 9/12-port dual tone. 9/12-port dual tone is much more common on the Penetrator-10 compared to its 15 horsepower counterpart. The P-10 was available in either single or 3 ph power.

The P-10 uses a chain-driven rotator, which is located underneath the siren. The siren's motor is coupled to a gear reduction drive that drives a shaft vertically through the siren towards the bottom, where it rotates a gear against the chain to rotate the entire siren unit on a stationary base. The chain itself is covered on top with a teardrop-shaped cover to protect it from the elements and is the same rotator that the 3rd generation Allertor uses. The rotator was also reused on early ACA Alertronic AL-6000R units, though rear-facing.

Due to the intake and projector being placed together, as well as the lack of a compression drum, the P-10's overall sound output is slightly lower than the Allertor 125, which has the intake and projector separate. As a result, the P-10 is only able to achieve 125 dB at 100 ft, 1 decibel shy of the Allertor. Despite its lower output than the Allertor, the projector's benefits such as ease of maintenance and resistance to ice more than make up for the performance loss. The P-10 was available with conical or cylindrical intakes, with the conical intakes being more common on P-10 models. The conical intakes are prone to collapsing, due to the bolts rusting out.

It can be difficult to tell a P-10 and a P-15 apart without seeing the tag, as they are visually nearly identical. The best way to tell them apart is the windup speed, as the P-10 will often wind up a bit slower. This is not always reliable, however, as 1 ph units of both models may struggle to reach full pitch with worn run capacitors. With dual-tone sirens being seen as no longer necessary after the Cold War ended, the P-10 was discontinued when ACA went bankrupt in 1992 and was not carried over during ACA's transition to ASC. It was likely decided that it was no longer worth producing both sirens when the P-15 handled the single tone rotor better.

P-15

The Penetrator-15 (also known as the P-15) was introduced in 1982/1983. As its name would suggest, the P-15 uses a 15 horsepower Baldor or Doerr electric motor. Other than motor horsepower, the P-15 is identical to the P-10, using the same core (except 8 port units) and body. The P-15 was available in both 8-port single-tone and 9/12-port dual-tone. The The P-15 is more commonly found with the 8-port single-tone rotor, as the motor is capable of handling it and its higher performance made single tone a more attractive option. The 8-port model of P-15 uses a larger 19-inch rotor unique to it, as the additional 5 horsepower over the P-10 allows it to use a larger chopper without issue. Single tone units are rated at 127 dB at 100 ft, while dual tone units are rated for 125 dB at 100 ft. The majority of P-15s use the cylindrical intake, though dual tone units occasionally have the conical intake due to sharing the same 18-inch dual tone rotor with the P-10.

A three-signal P-15 was available, which utilizes a solenoid-operated damper inside of the cylindrical intake, which would allow the siren to create pulse signals. The solenoid mechanism is housed in a rounded cover on the side of the intake. There was also a two-signal model that used a valve held closed by a spring. The valve would be forced open by the high volume of air drawn in when the siren began operating, and when the siren shuts off, the spring overpowers the weakening airflow and forces the valve back closed making the winddown much less audible. This was likely meant for urban use, silencing the siren quickly without using a brake or solenoid. It may have also been used as a weatherproofing measure. Three-signal units are very uncommon, with most active surviving units being in the Memphis, TN area, though none of them use their dampers.

RM-127

In 1992, the P-15 was re-released as the PN-15 and soon after as the RM-127, following ACA's reformation into the American Signal Corporation by HÖRMANN in 1994. The 9/12-port dual-tone option was dropped in favor of making the RM-127 exclusively 8-port single-tone, as the need for dual-tone sirens had ended with the end of the Cold War. The RM-127 would continue to be produced until 2002 when it was replaced by the ASC Tempest-128.

Werden P-127

After the RM-127 was discontinued in 2002, ASC sold the patents of the RM-127 and the Banshee 115 to the Ohio-based company Werden Electric, who built and installed their own variant of the single tone P-15, called the P-127. The P-127 is nearly identical in appearance and performance to a standard P-15/RM-127, sporting Werden's logo and paint job. Some units make use of a conical intake in the style of dual tone Penetrators, while others use a cylindrical intake. The P-127 was only produced in 8-port single tone, with no dual-tone units having been produced. Due to Clayton Werden's retirement, it is unlikely that more of these sirens will be produced.

PN-20

The Penetrator-20 (also known as the PN-20) began as an experiment by ACA in 1988 to create a "Performance Plus" fully DC siren using the Penetrator platform, with the ultimate result being the PN-20. The PN-20 uses the Screamer S-7.5's 16.5-inch 9-port single tone rotor. Using 9 angled throats around the stator ports to amplify the sound output (similar to a Federal Signal 2001), the PN-20 boasted a 130 dB at 100 ft rating by forcing all of its output through 9 horns attached to the front of the stator throats, with the outer projector projecting the sound emitted from the intake. The PN-20 uses a dual-sided 7.5 hp 240 V AC motor, which was hooked up to a DC-to-AC converter that ran the siren on 25 large DC batteries stored under the controller. This proved to be expensive and impractical, and as a result few PN-20 units were sold compared to the other Penetrator models.

The chain-driven rotator mechanism and motor cover are reused from the Penetrator-10 and 15 and parts are largely interchangeable between them. Most of these early PN-20 units were installed in Eden Prairie, MN alongside some Performance Plus P-15 prototypes, and few were made before the siren was redesigned. In 1992, the siren was re-released with some of its major flaws corrected. The 7.5 hp AC motor was replaced by a 20 hp 72 V DC motor, and the AC converter was removed. This allowed the siren to run on fewer batteries and made the siren overall more efficient, which reduced costs and maintenance requirements. ACA also experimented with a 96 V DC variant of this siren, which was otherwise completely identical to the 72 V DC version. This proved to be a failure due to excessive arcing in the motor, and this variant of the siren was not put into production.

ACA also experimented with other "Performance Plus" Penetrator designs, including replacing the P-15's rotator with an Alertronic's rotator and using a DC motor, but the 8-port rotor proved to be far too heavy for the motor and batteries to handle, leading to the batteries rapidly draining and the siren losing pitch quickly when operating. This short-lived design would be later replaced by the PN-20. An example of an experimental PP-15 was formerly in service in Eden Prairie, MN, but has since been removed leaving none left in existence.

RM-130

When ACA became the American Signal Corporation under HÖRMANN's ownership in 1994, the PN-20 would be renamed to the RM-130. Other than the decals and paint, the siren was entirely identical to the redesigned 72 V DC PN-20. The siren would remain unchanged for most of its lifespan until the late 1990s, when the gear reduction in the rotator was changed to rotate at 2 rpm instead of 3.5 rpm. This change was done near the end of the siren's production, and as such few of these 2 rpm units were made. As of 2022, all 2 rpm units have been replaced. The RM-130 was eventually discontinued in 2002 along with the RM-127 as they were both directly replaced by the ASC Tempest-128.

P-50

The Penetrator-50 (also known as the P-50) was introduced into ACA's lineup in 1980 as a replacement for the Hurricane 130 MKII, boasting incredible sound output without the need for a blower, which means the siren also requires less maintenance. The P-50 shares a rotor and stator with the ACA Cyclone 120 and is essentially a Cyclone 120 flipped on its side with a rotator and projector attached. The Cyclone's already incredible sound output is amplified significantly by the projector, allowing the P-50 to reach a staggering decibel rating of 135 dB at 100 ft, which makes it to this day the loudest electromechanical siren ever made, only beaten in sound output by the engine-driven Chrysler Air Raid Siren.

The P-50's 8/12-port dual tone rotor is 24 1/16 inches in diameter, one of the largest rotors used on a siren. The siren runs on a Doerr fan-cooled 50 hp AC motor, which was only available in 3 ph at 208-230 or 460 V. The P-50 is recommended to be run on 460 V, as the lower voltage models can draw over 100 amps upon startup. The motor is rated for continuous operation, allowing the P-50 to run for long periods of time without damage as has been demonstrated in an infamous incident involving one running for over half an hour.

The P-50 uses a massive, slightly flared fiberglass projector that focuses all of the output in a single direction. It consists of two sections bolted together with a mesh screen in the middle. The screen is mounted near the front of the projector on early units. The P-50 is an incredibly large siren and its projector was advertised as being tall enough for an adult man to stand inside the horn without having to crouch. An eyebolt is attached to the rear housing on all P-50 units for ease of installation.

The P-50 rotates at 3 rpm driven by a chain-drive rotator below the siren, which is contained inside a uniquely shaped housing that has enough clearance for the stand that connects the rotator shaft to the rest of the siren. Depending on the controller used, the P-50 will immediately stop rotating upon the chopper motor shutting off, as it is driven by a separate motor. The rotator will only continue operating while the chopper is coasting if the controller is configured to allow the control of the chopper and rotator independently.

The earliest P-50 units used a different projector design, which had a flat, wider ring around the horn where the inner mesh screen and the outer horn section were bolted. The front horn section was originally much smaller, with the two pieces being bolted near the front of the projector, though this was later changed to using two sections of equal length, bolted in the middle. Most P-50s produced afterward use a large ring in between the two sections where they are bolted together. Most of these early P-50s were painted yellow, while later units were typically painted gray.

RM-135/T-135AC

The P-50 was reintroduced as the RM-135 in 1994, when ACA was reformed into ASC by Hörmann, becoming the loudest siren in the RM series of sirens. The RM-135 was identical in design to the P-50, however, ASC's controller allowed the siren to continue rotating after the chopper motor shuts off, which made its attack signal more effective. When ASC was sold by HÖRMANN to Dale Moeller in 1998, the RM-135 would be incorporated into the new Tempest series of sirens as the Tempest-135AC. The T-135AC would ultimately be discontinued when the T-128's larger variant, the T-135AC/DC, was introduced in 2007. While the T-135AC/DC is not as loud as the T-135AC, it is battery backup capable and runs on DC power which makes it more reliable in an emergency, and uses far less power than the T-135AC which made it more economical to install and run.